What is special about this kind of animation is the same quality that is special about paintings in comparison to photographs. Photographs, particularly digital photographs, have a crisp quality of realism where paintings -- even spectacularly realistic paintings -- have a sense of the surreal about them. The same is true when comparing digital animation and hand drawn animation, the digital always "feels" a little more real than the hand drawn -- somehow more abstracted from reality.
Both types of animation have a well deserved place in entertainment, but sometimes we get so obsessed with the new that we forget the transformative nature of the old.
The Secret of NIMH is one of the rare movies that Jody and I own actual animation cells from and they are among our most prized possessions.