The only way to even *know* what readers might like is to allow them to read and share on the open Internet.
Knowing what it's like inside a media company, let me state up front that there are epistemological problems in deciding from the outside why The Daily failed. I've yet to see an article about The Atlantic that understands how our site works under the hood, and why that has led to a relatively successful few years.
That said, I do have a few thoughts about The Daily that I'd like to offer alongside my colleague Derek Thompson's.
1. The Daily was built on the false premise of a "general reader." When I hear general reader, I think that a media executive is imagining himself and his friends (you know, normal guys) and intending to produce a bundle of content for that hyperspecific DC-to-Boston-went-to-a-good-college-polo-shirts-and-grilling demographic. As a result, anything that falls outside the boundaries of the interests of this presumed Joe Six Pack will be deemed too "cool, quirky, nerdy, obsessive or snarky." That's not to say that such a publication will never run such pieces. My old pal Ben Carlson wrote quite a few. (So did Zach Baron and Sarah Weinman.) But you're fighting the institutional gravity. And you'll have to build defenses into the story that are the writerly equivalent of "I don't meant to nerd out here, but..." Because otherwise the bros running the grill will throw you in the pool.