|Ock and Wolfman no steal Hulk's popcorn!|
That's a much harder question to answer. It shouldn't be, but it is.
First, the movies influence quite a bit of influence over the comics. Comic book companies looking to cash in on movie success alter almost anything about their characters to make them more accessible to moviegoers. The X-Men changed uniforms, Spider-Man got unmarried, and the Hulk rejoined the Avengers. I can't think of another medium that is so influence by the movies produced from the source material.
Next, there's a real danger in planning future comic book projects solely to catch Hollywood's eye. That's like trying to create a video game going, "Gee, I hope Hollywood turns this video game into a movie!" No, you try to make the best video game you know how. If you're lucky, it becomes successful enough to warrant a movie.
Finally, movie success has failed to translate into actual comic book sales. I personally think the price of comics has a great deal to do with this but whatever the reason, the source material doesn't benefit like, say, the Harry Potter or Twilight books did. Since DC and Marvel are owned by movie producing companies already this puts them in a peculiar position. Are they comic book companies that happen produce movies or movie companies that happen to produce comics? The answer, more and more, is looking like the later.
Now it's not all doom and gloom. Certainly, a high profile movie can raise public awareness of your character greatly. Hellboy is one example of this. I think even Thor, the Fantastic Four, and Captain America were below the radar for a large percentage of people. Now they're part of the cultural language. That can't be a bad thing.
And money is money no matter how you make it. The fact that comic book heroes make tons of money only means that comic book fans will continue to enjoy a growing multitude of comic book options for the foreseeable future.
And don't forget about cross pollination - Sure, comic books spawn movies but the reverse is also true. Plenty of movies has been turned into comics. Some are one-shots, others are miniseries, but there have been a few quality ongoing series based on movies as well.
So are the movies good for comic books? I'll say this - I'd rather have successful comic book movies than not for the industry. So yes, movies are good for comic book industry.