I'll admit I do class Littlefoot and co as cute. But there are some scenes in the first film were they do look a little creepy and ugly... Mainly scenes when a character is unhappy. And boy did some of them creep me out as a kid.
I mean that shot of Cera panting after she tumbles over after Littlefoot accidently lobs those bones at her, the scene were Littlefoot yells like a maniac when he first see's Petrie... AAAAHHHHHH-HA HA!
And for me PERSONALLY from the 7th film onwards their cute factors dropped quite a bit with the digital animation, were they just look real goofy and silly.