I don’t know about you guys but I am dying for this game’s release, and primarily excited for the multiplayer aspect.
The fact that co-op was mandatory was a misconception that arose from Game Informer’s interview with Bungie’s James Jones. Bungie community manager Eric Osborne confirmed in the NeoGAF forums that you don’t need to team up with other players to play the story mission in Destiny.
He said, "You aren't required or forced to play any story missions in Destiny as part of a co-op group." He said that the single elements will hopefully get players more interested in the universe, and which is why they might opt to play with others. He added that the social experiences can be "incredibly powerful and interesting," but players have the freedom to go completely solo if they wish. Although, it's likely that some of Destiny's end-game content could require co-op:
"We describe it in a lot of ways as sloping the floor towards socialization, without putting a requirement on it. I would say that there’s some sort of--if you wanted to talk about it in MMO terms, you’d say 'end-game activities', but some of the most intense non-competitive activities in the game do require co-operation.
They require a group of players to tackle at once. I guess at some variable, distant endpoint we are going to say, 'Yeah, if you show up at this door, and you don’t have five friends, you’re not going to be able to succeed,' but the core experience that solo players have enjoyed in shooters, they’re going to be able to get that, and we’re going to pull many of them into social experiences as well."