No way.
Imagine being in the middle of a battle where they incorporate co-operative inputs for both players to help slay a monster. Or to perform certain attacks/spells you require both people to be in a certain vicinity. Or even certain combos and whatnot.
Co-op would work just fine.
I remember playing co-op Diablo for fucking hours, and that\'s as button masher as you can get. I\'m sure God of War would be fine.