>>34203925sprites allow one's imagination to take over because the sprite doesn't try too hard
3D-models try hard, and if they're bad it leaves less room for imagination to take over, and makes things like Ash-Greninja awkward to look at (eww... is that... hair coming out of the frog... next to its tongue scarf thing.... and Ash had an intimate bond with it?... fucking gross)
A better example than Giratina would be all the flying mons that just hover for the entire battle, or the water mons that all just levitate around the battle field - it looks stupid in 3D