[mladenkovacevic]

As a business they must realize that alienating users is against their business interests. I don't see what the big problem would be in leaving the thumbsup-thumbsdown options alongside the +1 button.

YouTube is a social network in itself (at this point a much more powerful one than Google+) so they have to respect its users and not try to force them to signup for the other network.

I don't personally vote on Youtube videos but I can understand how a video publisher might be upset that he's suddenly going to be getting fewer likes on his content.

Again it seems this was just a test, so considering the negative user feedback I certainly hope it stays just that.