A lot of people are freaked out by arachnids, insects, pretty much all creepy crawlies. That's why they are creepy crawlies and not loveable huggable crawlies.
Average real life spiders don't freak me out like they used to, but I still hate them. Giant realistic looking ones (like in modern fantasy games) still freak me out a bit, I think it's the eyes...or the fact that they are basically representative of many of my childhood nightmares.
It's actually kind of amazing how fast no-spider mods come out for games these days. Either a lot of modders are arachnophobes or even people who aren't don't like looking at them.
But even if you ignore all of that I find the idea of bears dropping from the ceiling and marching towards you on hindlegs to be hilarious.