For one guy I know, the N64's rumble pack was a purchase point. That and Zelda for some reason seemed like a cool enough combination to go for it.
Yeah, it was pretty cool for its day, wasn't it? But rumble doesn't really provide much... It's very limited in how it's used. I'd like to do a quick draw game, where you have to hold the controller really still until BAM it rumbles, and you've got to move!