I think this open votes thingy will end up with everybody giving +1 randomly and only massive trolls getting -1ed to death. People sometimes want to say some other people say crap, but without being seen. If two arguing people start -ing each other posts, the thread will not likely end up with a polite conclusion, as this only alienates people.
I hope somehow people will focus on the content, but it's obvious to me that if you see someone -ing a serious suggestion you wrote, you will just think it's hopeless to speak with that person.