Today, there are lines of "tween" girls all hopped up on Glee and Twilight. Movie studios utilize Comic-Con as a massive marketing opportunity, which is okay if you're promoting The Expendables but not so okay if you're trying to pimp Get Up and Dance 2 (ugh).
As a result, what was once strictly for the fans has now become mainstream. Mainstream = no bueno. So is this a good thing or a bad thing?
In my opinion, it's both. Think about how we, as fans, have benefitted from great movies such as X-Men and Spiderman and Iron Man. The more our beloved heroes become well known, the better. But there is a downside (*cough* G.I. Joe movie *cough*) in that sometimes in order to appeal to the masses, the essence of a character must become watered down and a bit more "middle of the road."
We can still enjoy Comic-Con. We can still wear our superhero costumes. We can still have arguments about whether the Thing could beat the Hulk. And today, we can now relish in the opportunity to tell "normal" people, "I told you so!" about how great comic books are. If nothing else, view it as an opportunity to laugh at the lemmings that don't get it. Booyah.