Matter of taste I suppose. I'm quite fond of her voice and her individual way of talking. It would be kind of boring to have them all talk the way fellow students do all the time.
There is more to make of her than a mere cutie. No doubt she is meant to be the cutie, but unlike some other movie's cuties she can act on her own without anyone else telling her what to do (examples in LBT 5, 7, and 8) though I will admit that most of the time she prefers following Littlefoot's or Cera's lead.
Interestingly she seems to be a "language talent" being able to give a more complex meaning to the baby talk of Dinah and Dana and the mumbling of her little brother Spike. She is especially helpful (it is difficult for me to imagine any of the others as Spike's surrogate sister or brother).
It is remarkable how sometimes she seems to be quite acrophobic, when crossing logs in LBT 2 (Spike has to carry her) and 6, while on the other hand she is the first to leap across the rocky pillars in LBT 6, which seems much scarier to me than crossing the log in the same movie (Spike too seems to have this temporary fits of acrophobia while he sometimes shows an extreme indifference towards heights, for example when he crosses the LBT 5 log smiling relaxed and with closed eyes).
Ducky is the only one with both parents in the Great Valley, though we didn't get a glimpse of her father (who never played a role) since LBT 5. Maybe this contributes to her being probably the most cheerful of the LBT maincharacters.