On TV, the concept of "popularity" is easy to measure and hard to understand.
In music, the most popular songs are inescapable, and their artists become national celebrities. In movies, the most popular films are feted in the Monday papers and widely acknowledged, even if they only compete for the special-effects awards in March. But on television, the world of criticism and the world of viewership aren't merely askew; they're mostly on different planets. No self-respecting TV critic writes about NCIS: Los Angeles, ever—ever—even though the all-time most-popular episode of Game of Thrones (which is, itself, the all-time most-popular HBO show) got fewer viewers than an NCIS: LA rerun. As I wrote a few months ago, the most essayed-about show (Girls), most tweeted-about show (Pretty Little Liars), and most buzzed-about show (at the time: House of Cards) sum to half the average audience of NCIS (which is hardly essayed, tweeted, or buzzed about at all).
More than other entertainment industries, TV seems to play by the rules of a peculiar Faustian bargain: Be popular and scarcely acknowledged; or be praised and scarcely watched.
This bring us to The Big Bang Theory, which deserves a theory of its own. The Big Bang Theory is not merely the most popular comedy on television, besting its nearest rival by a margin of 10 million viewers. It's the most popular comedy for every demographic between the ages of 12 and 54 and, more importantly, the most popular show on television in 2014. An estimated 84 million people—equal to the combined populations of California, Texas, and New York—have watched at least six minutes of it this year, according to a marvelous new investigation of the show's popularity in New York magazine.
Not unlike the big bang, itself, a good theory for what makes the TBBT so astonishingly successful requires empirical evidence, but ultimately its full explication is, perhaps, beyond the limits of human knowledge. On the empirical side of things, there are four key factors: Chuck Lorre + CBS + Thursday + Syndication. That is: Take a formula-driven buddy comedy by an experienced showrunner with a proven meta-script (put average guys in awkward situations and add lite-raunchy humor), add the power of a CBS audience (it's by far the most successful programmer among the networks), give it a Thursday-night slot, and finish with the redoubling effect of heavy syndication on TBS. On the less-empirical side of things, people seem to find this show really funny.
So why doesn't popularity demonstrated by CBS's formidable line-up translate into much attention from the press, which in many industries (entertainment, politics, sports) covers what is popular simply because it's popular?
There's a shallow and deep explanation. The shallow explanation is that TV I (and perhaps you) live in the cloistered monastery of media. Television criticism thrives with unpacking precisely the sort of shows that don't appeal to a mass audience, because they weren't made for a mass audience.
Which leads to the deeper, economic explanation. Broadcast TV sells audiences. Premium TV sells a "brand." That's how HBO's Richard Plepler, speaking yesterday at The Atlantic's New York Ideas conference, summed up the difference between what he does and what broadcast television—e.g.: NBC, ABC, CBS, FOX—tries to do. HBO makes all of its money from selling subscriptions (to the HBO channel) and selling shows (e.g. to Amazon and anybody else). Broadcast television, however, has an entirely different business model based overwhelmingly on advertising. Among the broadcasters, ad money follows audience.
The macroeconomics of TV aren't invisible to consumers. They are incredibly visible. You see them every night. HBO can afford to produce risky niche entertainment because its success is determined, not by maximizing the ratings for each show, but by making just enough original programming that keeps its subscribers from canceling. If a significant share of HBO's audience only watches one show a season (say: Veep), that would be a triumph. If a significant share of CBS's audience only watched 30 minutes of CBS a week, it would be an unmitigated disaster. HBO is hunting sign-ups, so it can afford to downplay ratings. CBS is hunting eyeballs, so it can't. And so CBS and HBO can both be thrillingly successful on their own terms, even though one channel makes formulaic popular stuff that nobody writes about and the other channel makes much less popular stuff that absorbs the attention of TV media precisely because it isn't formulaic.