I still remember when you could rate videos on a scale of 1-5 (or was it 0-5?), and it showed the average rating from everyone who did. Then they made it a binary like/dislike, and now the trend continues to making it unary...

IMHO the "like/dislike" mentality is partly responsible for the divisive hostility of culture today. You either like something or not, you're with us or against us, there's no middle ground.