I'm okay with someone not agreeing with me. I'm okay with someone downvoting me.
Someone downvoting everything I have and will ever make? Well, there's a magazine I'd love to get more folks in and this behavior could cripple it badly, since I get next-to-no votes in there from others so it's already difficult to get more eyes on it. But other than that I think I get more agreements so I wouldn't care that much.
Therefore I'm happy that there's an upvote and downvote (and a reputation) system.