Reputation?

[Ixus]

One like for you George

[JiggeryPokery]

There's also another issue this raises, when people start having personal vendettas and start wholesale disliking every single post from a member. There is some seriously childish shit that happens as a result of those two little buttons.

People who have personal vendetta's won't limit themselves to merely clicking thumbs down icons. Bullies and trolls feed off attention, so will always comment and eventually they'll be banned if behaviour is abusive.

If all they do is downvote that's beneficial, rather than actually saying unpleasant things.

Dislikes really don't mean a great deal unless you let them: without an actual opinion in words it's largely meaningless, so allowing dislikes means that people as a group can say "we don't like this" without actually having to always get into a textual slanging match. That's how flame wars start - people constantly responding and having to have the last word, so it's an ongoing circular debate that gets more and more vicious.