Well, I've never bought a comic book in my life, and I care about relative believability.
It's not just a problem in comic book movies. Every movie you go in needing to accept some (often ludicrous) premise. Heaping coincidences and other unlikelinesses on top of that premise weakens the movie.
For instance, I watched "Untraceable" the other night. It asks you to accept the title premise, that somehow this particular killer's web feed is really untraceable, despite it being easily routed by the internet DNS servers (not to go into details, here, but they pseudo-explain this by saying he's broadcasting his source feed to a bunch of botnet drones, and the DNS entries re changing the one web site URL to a different drone with every request, and for some unexplained reason they can't just bring one of these drones in to see where it is getting it's feed from). Since it's the title of the movie, and I already groaned when I saw that in the trailer, I accepted it. And since it's a serial killer movie, I also accepted that the killer had some unnatural set of skills at hacking bits and hacking people. That's premise. And it's a whopper of a premise, already pushing the boundaries of acceptability. Note: spoilers of a bad movie follow. But then the writers throw in every possible serial killer movie cliche coincidence: the FBI agent who is meticulous about everything lets her daughter surf the net and download apps from "friends" to run on her (presumably secured) home machine which also happens to have all her FBI files sitting on it unprotected; the other FBI agent engaging in blind Internet dates gets targeted by the killer right when he happens to figure out the key to the case; said FBI agent calls heroine but instead of telling her the key to the case tells her he'll tell her later, right before he is snatched by the killer, and the "key" turns out to be two words which he "blinks" in morse code to her; another FBI agent who knows morse code sees the internet-dating agent blinking and "knows" that left eye is dot and right dash so he can get those two words written down .... blah blah blah. At this point, you've blown past the premise and the movie is schlock.
As a general rule, since you asked, a good non-absurdist story will have a central premise of a single unlikely event, perhaps two (kid bitten by spider gets special powers; world is going to end in 2012), and other unlikely events either follow naturally from that one unlikely event or spring from the same cause as the first unlikely event. In today's movie, it is rare for that premise event not to be spelled out in the trailer, so you are guaranteed that the folks who are sitting in the seats have either accepted the premise or are placating someone who accepted the premise. Once the premise has been accepted, additional unrelated unlikely events (various other superheroes/villains spawning due to unrelated accidents; guy happening to come across all the information the 2012 guy comes across AND happens to survive everything even though the information he came across played no part in that, etc) weaken the story, bringing the viewer back "out of" the story.
Again, you don't need to be a comic book geek to care about this. It's a central characteristic of all good non-absurdist writing, that aside from the premise, all facts are internally consistent and believable.
"Absurdist" writing (say, just about anything from Chuck Palahniuk) is the exception, here, as the unlikeliness of what follows is the entire point.