Just my 2c, but if you want OC heroes, make an OC hero game. FC games should be FCs. Mixing them is asinine.
Honestly, the pure audacity required for a player to think whatever harebrained thing they whipped up in 30 minutes deserves the same attention/etc as a comic book character that's been written for 10, 20, 30, however many years and is known by 80% of the players on the game, and has been in cartoons and movies and whatever else is just...
Seriously? It's dumb. Pure and simple.
Very, very, very few people go to a comic game because "oh man I can't wait to see what OCs people have created!"
People who play OCs on comic games are basically taking advantage of people's kindness to throw a wrench of concentrated stupidity into the cogs. You're a burden on the rest of the game. Staff hates doing OC apps. Players tend to hate having to spend their time with OCs trying to join their teams.
"Oh man, I finally get to do a scene with <Insert Comic Character>! I can't wait to see what angle the player takes them in. ...Oh, jeez...this OC nobody cares about is coming too? Ugh."
If everybody is an OC, hey, I have no problem with OCs.
When you're mixing Spider-Man and Cyclops with 'pile of nonsense somebody whipped up one saturday afternoon', that's pretty weird.
ETA : Something no Jean-player has ever said --> "I sure wish this game had more teenage mutant OCs pining for attention."
OC players go into comic games with an entirely different mentality than the other players.
OC players almost infallibly tend to be seeking 'validation' through attention from FCs, whereas FC players tend to just want to tell stories with other FCs.