The biggest reason imho is that the entire enterprise market is going to eschew these since they cannot ask their employees to log into personal Facebook accoun

The biggest reason imho is that the entire enterprise market is going to eschew these since they cannot ask their employees to log into personal Facebook accounts. Throwing out the whole enterprise business market for this is insanity in my view. Facebook has a real chance here to be the owner of the next, possibly last great computing platform - but not if they hobble themselves like that.