yes, yes, yes I always have some dopey AI companion in Bethesda games and am constantly thinking about how cool it would be to run with a party of people, it could lead to much better combat and role playing as we could definitely go the DnD rout, building a solid team and using our combined skills to defeat enemies and finish quest's, I really fail to see why skyrim would be ruined by having 3 friends with me while I play, it's a game about exploration, questing, killing dragons and having other shenanigans all of which sounds much better with friends.
just imagine the epic dragon fight where you and 3 friends, a warrior, a archer and a mage all have a hard time fighting just 1 badass dragon