because making fun of a superfluous misrepresentation of my argument's doing a great job strengthening yours.
movies are products, but they are entertainment nonetheless. comics, also products, are also forms of entertainment. there's really no reason for the majority of the changes in the movies, as the movies turned out poorly anyway in terms of plot and acting. a movie that stuck more closely to continuity would likely have done just as well, and not gotten such a negative feedback.
and here's the real ringer; complaining about bad movies is universal. my girlfriend, an avid harry potter fan, spent the whole hour trip to the theater bitching to me about things she'd heard were wrong with the movie (before she'd seen it.) "they're too old, they'll have to drop a lot of the information, the special effects can never match up to what's written in the books..." and she spent the entire ride back, after seeing it, complaining about everything else. the same always-complaining principle happened with the blade movies, all of which sucked, it's happening with the buzz around the narnia movies, people have mixed opinions about fight club... any movie "based" off something else is subject to this type of stipulation. so, as much as you're entitled to "giving it a shot" before judging it, others (including myself) are entitled to take what we know about the movie and form presumptive opinions on it.
edit: x, all of the changes they made, in hopes of setting up certain "dynamics" or appealing to certain groups, could have been done within the confines of the comic universe without causing any "confusion" for non-readers. the changes, which clearly show the emphasis was put on fluffing out a sellable story as opposed to adhering to continuity, just weren't necessary. they could've strapped a load of comic writers to the script, and let them find better ways to portray whatever scenarios and emotions were desired, without getting confusing and without abandoning a boatload of continuity. why shouldn't it be understandable for comic fans to be disappointed with a movie diverging from a "movieverse" representation of our hobby? it's like expecting philadelphia natives to cheer for any team named the eagles, even if it's just some random team in the mid-west.