Readers chime in on the improvements in kitchens.  

KAHoover plugs for the dishwasher as an extremely important invention:

Two observations: the greatest labor-saving device in the kitchen is the dishwasher. I cook in two kitchens, one a country house with and our apartment without. It takes the same amount of effort to do a complex meal for sixteen with a dishwasher as a simple one for four without.
Rob Lyman points to improvements in floor technology:
Here's another thought: I remember TV ads from my childhood for cleaners intended to be used on "no-wax floors." Anybody here ever wax a floor?
prompting this response from a reader who sure has:

Yep. But I think I'm old enough to be your mother so that makes sense.

Back when I was a newlywed (during the Carter administration) I used to wax our kitchen floor. Not something I'm nostalgic about at all.

And by the way, I still can tomatoes every summer - our homegrown ones (in my blessedly air-conditioned kitchen). Our three sons used to help me when they were little and one of them still remembers the process fondly and has done it a time or two as an adult.

My mother was a newlywed in the early 50's, and I remember how she cooked when I was growing up. The food was a lot simpler than we tend to eat now, less spices and a lot less variety.

One reader argues that I've missed the point:

I think you, and the blog mistress, miss the point Cowen and Krugman were trying to make. It's not that innovation hasn't taken place, it's that innovation hasn't led to totally new things(or ways of doing things). I'll give you one non-kitchen example. Take the iPod. That's not really a new innovation. It's just a newer version of the Walkman(remember those?) when you think about it.
Of course, the same could be said about virtually anything: it's all just heating up the food until the sugars carmelize and the proteins break down and coagulate in a tastier, more digestible form! A point that Christ_T_T emphasizes:

This is true of virtually anything humanity has ever made! There is no such thing as a singular invention as people seem to be imagining! Technology is a process of constant refinement and always has been. . . . Chemical refrigerants can be dated to the 16th century and insulation was improved throughout the 19th for shipping ice over long distances. Ice has been used for preservation since antiquity.

The theoretical underpinnings were fleshed out throughout the 19th century (electromagnetism was described by Maxwell in 1864 and his equations remain the basis of modern radio).

A primitive electric motor was demonstrated 1828, although it wasn't recognized as useful for anything. An early version was actually commercialized in the 1830's, although it didn't lead anywhere.

Telephony was a direct result of the telegraph. The basic idea of transmitting voices electrically was first broached in 1844 and some of its principles were worked out in 1854. The first crude transmission of a human voice may have happened in those decades, although it's heavily disputed. Quite a few people were working on telephony in the 1860's-70's; Grahm's phone was simply the first practical iteration.

All of these owe their existence to electricity and its description as a phenomena in 1600 and the work by many people over the next couple centuries.

Another reader questions the magnitude of stove innovations since Franklin:

I am guessing that Krugman doesn't cook now. He just goes into the kitchen to get a beer. That explains why he notices the fridge (the one appliance that changed between 1918 and 1953). The stove--a middle-class urban family would have had one in 1918--the food processor, the electric mixer, and the microwave are mysterious to him.
Kristian Halvoet says:

News Flash! Cooking hasn't changed much in a 1000 years!

More seriously, what do we cook today that can't be cooked using equipment available in 1900? Look at cookbook recipes. They involve cutting, mixing, heating (or in rare cases, cooling) ingredients in a specific order at specific temperatures. Yes, there are a lot of techniques involved, from sauteing to reducing to creating a proper mouse. Not a single one of these techniques was created in the last, what 200 years?

Cooking is a mature science. There are incremental changes, but we hardly can expect revolutionary changes. I would even go so far as to say the change from green to powered kitchen appliances (HA!) was not a great change, as it did not change the food prepared, but MAY have saved some daily workout time.

We use stoves, grills and ovens. All of which are hundreds (or thousands) of years old. We cook on metal, glass or stoneware pans (and for all the new tech, a cast iron skillet is STILL a cornerstone kitchen implement). We use wooden, metal and a few plastic/silicon stirrers. Most gadgets really aren't worth the space they consume. We measure volume, and weigh materials.

Unless you are talking about robot chefs or replicators, we are probably going to be cooking the same basic way for the next 200 years.

Derek points out that many revolutions are invisible to the end-user: should they count?

There is what could be described as a revolution in electric motors going on right now. Motors that drive the fans in your furnace, circulate the air in your fridge. Just one example. Of course, it looks the same to someone smart like Krugman.

This stuff has been around for quite a few years, but the further revolutions in production technologies have allowed them to be used in consumer devices.

I use revolution purposely. What it means is that everything you knew before doesn't apply any more. From the outside it looks the same.

Stefanstackhouse reminisces about his produce-poor childhood:

When I was a child in the 50s and 60s in small-town Indiana and Michigan, I remember that the only fresh fruit generally available year-round were apples and bananas. Oranges and grapefruit were available in the winter, and berries and melons in the summer. I remember seeing a TV ad in the early 60s inviting people to imagine how wonderful fresh strawberry shortcake would be in October, but you can't get them then so you better enjoy them in June when they are available.
And reader Celiedth drives the point home:

Let's not over romanticize the scratch cooking of the 1950's. 'Seems to me it had a heck of a lot of cream of mushroom soup, canned veggies (you've never had disgusting until you've had canned peas), and my alltime childhood favorites from Chef Boyardee. It was also the heyday of the TV dinner. My husband's favorite was his mother's recipe of Uncle Ben's rice served with canned tuna and canned pineapple. Dessert was inevitably jello.
Many readers point out the folly of over-romanticizing fresh produce; it's hard to be a locavore if your agricultural land is snowed-over six months out of the year.

Megan is right to mention how much canning was done in the Olde Days. My grandmother did huge amounts of canning, as we found after she died in the early 80s. There were mason jars in the root cellar in the basement that had been put up in WWII. She did all her baking the old fashinoned way with hand mixers and wooden spoons. I prefer my Kitchen Aid.

One trend among chefs and foodies that I find stupid is the locavore movement. I don't mind supporting local farmers and crafters for ingredients. I buy from them myself where they make products I like. (St. Arnold's Brewing is heartily supported in our household.) What I do find off-putting is the moral smugness associated with the movement. Look, it's easy to be a locavore and only eat food produced within 1-200 miles if you are in California, where some of the best agricultural land in the worlds is in the area. What are you supposed to do in parts of the midwest? Live on chicken, pork, beef, corn, soybeans, sorghum, and wheat? No rice, citrus, most fruits, or green stuff? No coffee or tea? No beer? I understand the impulse and agree with some of the environmental reasons behind it, but it's asking a lot for those of us in flyover to go back to midwestern boiled dinner all the time.

AnirProf agrees:

Agreed. It is totally unsurprising that ground zero for the locavore and electric car movements is northern California, where you can find anything you want, from cacti to chunks of glacial ice, within a couple of hundred miles. And where the climate is such that electric cars don't face battery-killing subzero nights, don't need to run big heater loads during winter driving, and don't require big air conditioner loads half the year. They enact anti-growth zoning codes that prevent the rest of us from joining them in the garden of Eden, and then look down on us for not limiting ourselves to licking road salt off the snow banks in the winter.
Other readers point out how hard women had to work in the 19th century:

ANY washing machine - even the old wringer kind - were a hugely welcomed improvement over the old ways of doing laundry. Before washing machines, every household either was full of related women (housewife plus grandmothers or aunts or daughters) to help with wash day, or else they needed hired servants. This is one of the main reasons why houses were bigger back in Victorian times than they are now. It was not just because they had more kids. Even if they didn't have many kids, they still needed more people in the house, because it was just too much work for one woman to do all by herself.
JonF311 adds:

Also a reason why divorce was less common, beyond the legal hassles. It was virtually impossible for a person to live alone until the 20th century: even ascetic religious hermits realized it was almost impossible and formed monastic communities instead. If you couldn't afford servants you needed a helpmete, and single people generally lived in boarding houses when not with their families.
Other readers focus on how the internet is still changing our cooking:

My kitchen, and the food that comes out of it, has benefited greatly from a number of innovations from the last 50 years, from the seemingly low-tech (but apparently non-trivial to manufacture) Microplane to the instant-read thermometer.

But the most important tool in my kitchen is the laptop computer (or, when I can wrestle it away from my 2-year-old, the iPad). Within minutes I can find a dozen different recipes for the dish I want to make, get a gist of the variations, understand the essentials and become an instant expert. Pre-internet, even with a library full of cookbooks, this would be very difficult to pull off.

But a one user dissents from the past-bashing:

Y'know, there are benefits to coming up from a Mennonite/Amish background. Never mind the modern appliances, I've eaten some damn fine meals in kitchens that don't even have electricity. Yes, there's more manual labor involved, but remember, this is not in addition to another job. The family's living on one income. All that time gardening and canning and cooking comes out of time not spent at an outside job, earning money so you can buy all the gadgets that make it possible to whip up dinner in half an hour out of foods purchased at the grocery store.

I don't think the overall level of effort has changed that much.