I was about in the same age range as you when I first saw it.
In any case, it doesn't seem right to jump on people because they found something scary that you didn't find scary. Heck, some people find stuff like Jell-O and cotton balls scary--do you jump on them for that?![]()
As for what I was scared of in it, there was the part where the air conditioner went mad, the part where they all ended up in the appliance shop, the part where Kirby short circuited (and almost "died"), and I think I vaguely remember one of the appliances being struck by lightning or something which scared me utterly crapless. I don't remember as the last time I saw it I was about 10 or so (and wasn't as scared then of it). The animation and art style didn't help so much either.
Almost any cartoon with a kinda wobbly, dark-looking art style (while Brave Little Toaster was colorful at some points, it was downright dreary for most of the rest of the movie) and off-kilter music was prone to scaring me back then.