Yep, definitely noticed that on reddit and here. I'd say having votes is positive overall for bigger communities but when everyone's optimizing for votes, it subtly changes the nature of the comments. That's not neccessarily negative but it sometimes seems to have a similar effect as when people are in front of a camera.

I visit one community website about linux (non-english) that doesn't have voting and I really like the natural, down-to-earth discussions and arguments (usually about current issues, politics, etc.).