According to the good folks over at ‘Screen Crush’, Kevin Feige from Marvel Studios said ‘Marvel’s The Avengers’ was almost given an R rating. Their whole article can be found here.
This makes a lot of sense to me. Comic book fans are used to seeing things like Blue Beetle getting his brains shot out through his face, Captain America hitting someone in their face with his shield, or Wolverine snikting people all over the place, non comic book fans aren’t necessarily immune to this type of violent imagery. I’m glad they made the cuts needed because they opened the film to a much larger audience.