Apparently, in the fifteen years since Watchmen was published, the bar has been significantly raised regarding how much over-the-top violence required to parody/subvert over-the-top violence in comic books. To be fair (to myself or this book; I'm not entirely sure which (ultra-violence is not really my thing. It's not exactly a subtle or multilayered story, but it does what it does with a certain verve that I can't help but appreciate.
I haven't seen the movie, but apparently it seriously soft-pedals two important plot points. Without that origin and conclusion in bleakness and nihilism, the element of subversion isn't there anymore and neither is the point.