I also thought Uggs were popular first - at least that's what it seemed like here (I know Uggs have existed for a long time, but that's beside the point).
I don't actually mind them that much, though.. I've never had a pair, but they look incredibly comfortable, and I wouldn't actually think twice if I saw someone wearing them as regular winter boots, as long as they were appropriate for the weather, ie. snow or just general cold, and aren't worn with, say, a mini skirt or shorts. I have actually considered buying a pair to use as winter boots, but decided not to, for various reasons. All these different kinds of furry boots, however, are fucking awful.
As for Crocs, they are insanely comfortable (I have a pair for my summer job at the hospital, that I also sometimes wear at home, but it's one of the more discreet models), but it's not like (most) people wear them because they are fashionable, so criticizing them for being ugly is sort of pointless, imo.