I completely agree with the original post. While the Spider-Man and X-Men movies make lots of money and were fine, they were still full of one-liners and camp. Not as much as there used to be, but it was still there. There were, what, two one-liners in TDK? And no camp, as far as I can tell. It changed a Batman movie from being a superhero movie to being an epic crime drama. Which is what Batman is. There have yet to be good, serious Spider-Man and X-Men movies. As for 300, well, I thought it was cool but it was shallower than a bathtub. A good adaptation I guess, if the source material is really that shallow.
My point is that had Watchmen just come out, maybe critics would see it for it's genius (IF the movie turns out well), but a lot of the audience would say "What? A superhero movie trying to critique society and it's own genre? What? No, that doesn't happen. Superheroes aren't like this...." But now that a popular character has been done seriously for the first time, and used to critique itself (in a way), it does open the door for a bigger critique of the genre. So yes, TKD opened the door Watchmen.
And a redband trailer would be awesome.