But it's just how Hollywood works. Trend followers. Obviously, since The Dark Knight made the most money ever, people want all of their super hero movies to be "gritty". And apparently, because JJ Abrams and Michael Bay successfully took old franchises and made tons of money from them, it's suddenly OK to re-make any movies that are more than 5 years old. I've been fairly mellow about the reboot thing so far, but come on, seriously, rebooting a critically and commercially successful franchise just because Hollywood thinks people now want to watch new versions of the same thing over and over and over again only darker and grittier, that's just appalling.
Of course, leave it to Hollywood to put all the success of a film on its tone. The Dark Knight didn't become the world's #1 blockbuster because it was dark and gritty. It's because it was well made, exciting, action packed, had Heath Ledger, TONS of hype and was based on a popular comic. Plus, it was dark and gritty for a good reason. It wasn't dark just for the sake of being dark, it was dark because that's what the Batman comics are like, which appealed to the legions of Batman fans. The original Spider Man wasn't exactly gritty, but it was still emotionally powerful and incredibly well made. In my opinion, Sam Raimi's first two Spider Man films were better than The Dark Knight. And they were successful even though they weren't gritty. But Hollywood doesn't care about that, so don't be surprised if you see Clark Kent contemplating suicide or Mr. Fantastic having to choose whether Dr. Doom blows up The Thing or The Invisible Woman.