"Marge, may I play Devil's Advocate for a moment?"
"Sure, go ahead."
Well, that's what makes America great, ain't it: reactive internet outrage over a movie muscle suit. But consider this: the audience for Watchmen will be overwhelmingly folks who don't know the difference. People who have never read Watchmen. Most of them have never picked up a comic book since they were kids. Many of them will say "Oh, are they still printing those things?"
Don't get me wrong. I agree that there are certain elements of a work of fiction (comic book or otherwise) that seem essential to the making of a movie, but I don't necessarily agree that the changing of a costume negates the point of the movie. Moore's idea that Dan Dreiberg has turned into a sad sack of an ex-hero may not necessarily be part of the movie screenplay. And while it was a rich portion of the book, I can certainly visualize a movie still being effective without it. They can't fit everything in.
More to the point, there has to be a certain amount of sacrifice fans are going to have to put up with, because the movie isn't being made for us: it's being made for Joe Q. Public and Susie P. America. While it would be nice if every element conformed to Dave Gibbons's design, it would not be practical on the screen, either visually or economically. (And I actually think that movie would be a little scary to watch).
Movies have a different visual and storytelling process than comics. An occasional Sin City aside, comics are not going to look and pace like movies/movies are not going to look and pace like comics. And usually, the things that fans complain about generally wind up being sacrificed for storytelling clarity, pace, and timing. And generally contribute to a better movie. No mechanical webshooters for Spider-Man. No Tom Bombadil in The Lord of the Rings. Or the Scouring of the Shire, for that matter. Heck, Michael Keaton's chin, which was one of the biggest fan-related uproars of 1989.
I'm not trying to say that this movie is assured to be good. Alan Moore novels don't have a good track-to-film record. I certainly hope it is good and pleases the fans as well as the larger percentage of moviegoers who will outnumber us umpteen to two. But don't forget the forest among the trees: the Watchmen movie is not gonna fail because Nite Owl has a more professional looking suit, or because Ozymandias has a codpiece.
In the words of Ham Salad: "Take it easy, kid, it's only a movie."