I'm one of the few that doesn't mind it. I already linked a Google+ account a long time ago, so it doesn't really affect me. I can see why it would bother some people though. I do prefer the threaded comments to the old system. It makes seeing replies a lot easier, easier than endless "show the comment" chains, at least. My only real complaint is you can no longer post a time in a comment to link to that spot in the video.