Google is simply trying to unify their services. YouTube was an acquisition, with it's own login system and social network. They don't want to maintain this separation forever, they want a single signon for everything. Ditto for sharing and contacts. You had separate 'contacts' in Gmail, Latitude, G+, Reader, YouTube, and probably others I'm missing. Users shouldn't be prompted to maintain N different copies of this…
"Google is simply trying to unify their services." Right, well, that's the problem. Google wants to unify their services, but I don't want to use the thereby unified services, which are, after all, conceptually distinct anyway. The complaint is that they're trying to unify their services. The explanation, when faced with that complaint, that they're trying to unify their services is a non-starter.
I mean, I'm sorry you feel that way. But it's an indefensible position.