In all honesty the negative ratings are rarely used.

Iwaku uses the same thing and almost everyone across the board has about 100+ likes for every dislike, no matter how unpopular/unliked the person tends to be, so it's honestly something where after having seen it myself I don't think is much a necessity.

Though funny note. :P
There was one exception to the 100+ likes vs dislike rule: Rare. XD

Rare has even more dislikes than likes because he once posted that suicidal people should just kill themselves.