[macavity23]

An interesting question - that was my first thought on seeing the headline too - "Why categorize everyone who's expressed dislike a 'hater'?"

I can offer no better explanation than Man's tribal nature - his tendency to form In- and Out-groups (http://en.wikipedia.org/wiki/Ingroups_and_outgroups). Before we had tech we did it about red vs blue football/etc teams (and of course still do), which is equally if not more arbitrary.

I'd like to think we'll grow out of it, but that's probably a vain hope, and even if we do it'll be a loooooooong way in the future.