Why is a world with less negative (unwholesome) qualities better?

Buddhism encourages people to get rid of certain negative qualities like anger, hatred, jealousy, selfishness. But, considering an evolutionary perspective we couldn't completely tell what role they might be playing at a deeper level for the advancement of species as a whole even if they do appear bad on the first look. So how can we be sure that a world without those negative qualities would be a better one.