I think the main annoyance that comes with Aerith (and with Sephiroth, for that matter) is not because of in game things (though I did hate her in the game, as well) but because of the fans. The rabid, frothing at the mouth, 'omfg plz remake VII and bring Aerith 2 lief agin!'. It gets more and more annoying, drives me absolutely insane hearing all this stuff about Aerith all the time, all the internet Aerith is better/Tifa is better fights (and yes, both sides annoy me there), etc etc.

Everyone in this thread has made wonderful points. The reason I didnt like Aerith, in game? To me she seemed fake, like she was trying to be something she wasnt. Trying to tag along with Cloud constantly, flirting with him directly in front of Tifa, being annoyingly cutesy and rather helpless, all of these things sort of pooled together to put her on my bad side. I was happy when things went down, in fact I watched the scene quite a few times.