The fact is, Bendis was a key part of an initiative to change the whole flavour of the Marvel line. To make it more "real World" (whatever that means when you're dealing with gods, people who can flay and lift trucks, etc...). To give it a more independent feel (after all, independent comics are where the real writers are, super-hero comic book writers are shmucks). AS a result, the MU became this huge pot of intrigue, killing, backstabbing, wetworks and black ops, where nobility and true heroism are foreign concepts (hence, exactly like the true world). As with other past concepts (nothing old can be good), the original Avengers concept is stupid. "Earth's mightiest heroes getting together to face enemies no single hero can defeat"? What's the big deal? Boring. Much beter, "some cool and popular heroes get together to eat, talk trash and, occasionally, get of their butts to join huge fights, where other people end up saving the day." Much more "realistic".
(Add a whole lot of overblown sarcasam while reading the sentences above, but the essence is truly felt).
Nowadays, I feel like Marvel is like one of those big Hollywood studios, where suits who know absolutly nothing about story telling come up with these "great" ideas that will sell and editors and writers have to bend backwards to make them happen (And, yes, at least in relation to Avengers, in my book, Bendis is one of the suits).
"You know what would really sell? NINJAS! Everybody loves ninjas! Let's do it!"
"No, I know it. I know it. (See the repetition? That really is how real people talk.) Gangstas! Let's make it happen."
And they put Little Red Ridding Hood with two guns leading a bunch of generic bad guys.