In a recent interview, Alan Moore said, "The thing that I most regretted about Watchmen: That something that I saw as a very exciting celebratory thing seemed to become a kind of hair shirt that the super-hero had to wear forever after. … [T]hey've all got to be miserable and doomed. That was never what me and Dave intended."
Even Moore wanted to lighten up superhero comics a bit, with Supreme and Tom Strong. Top Ten has grim moments, but the characters aren't "miserable and doomed."
Watchmen helped kick off a decadent death spiral that would see adolescent violence peddled as adult content full of rape, murder, and corpse-burning.
Sounds about right, mostly done at DC. Marvel just killed off the original Captain America and turned Iron Man into a quasi-fascist, and that was before putting Norman Osborn in charge so every Marvel hero can be as miserable as Spider-Man.
There's also talk of how non-superhero comics didn't catch on. IMHO, the closest comic about "average folks" that gained popularity was "Strangers in Paradise," and even that had Katchoo as an ex-secret agent fighting against her former boss.