- The hero never dies (because we want sequels).
- There has to be a villain (because we want conflict).
- There has to be over-the-top action (because everyone is superhuman).
"HULK WANT TO TRY DIPLOMATIC NON-VIOLENCE TREATY!"
It becomes really difficult to inject elements of other genres when you have to stick to that road map in order to be successful. You can't have high levels of tension or drama in a film that has already announced its next two sequels. That's why absolutely no one was fooled by Nick Fury's fake death scene in Captain America Strikes Back.
Yeah ... It's kind of hard to feel sad when you know he's contractually obligated to not be dead.