It can work someplaces. Mostly cartoony stuff with lots of inertia like Sonic games etc. You picked a wrong example with castlevania because I finished POR on DS and loved it to bits BUT the freakin' walk-cycles. They're so bad. Not only do they glide, not only they're oversmoothed, not only are the actual runs extremely artifical and silly, they're also SEMI-SIDEWAYS. On a fully side-ways, no perspective platformer. They're humanoid, and look very bad.

Haha, personally i really liked how they moved kind of gracefully as if not even touching the ground. It made the controls feel really smooth and precise. I think it's more of a gameplay decision since in some previous games the walk cycles were exact and solid and looked really nice, but the controls were really clunky for me at least. They probably wanted the character to move faster but still wanted to keep the rather slow walk animation. Also i think the sideways thing looks better than something flyswatted. They probably wanted that just to make the character strike a cool pose when idle and to have more room to play with stuff like the clothes flowing around the legs and so forth. The DS games had a lot of things that sought to break the swatted-flat feel from the snes games. Stuff like 3D backrounds that change perspective as you move and so forth.

Back to the original topic, i think it's really hard to match gameplay and animation issues. If the character walks in a linear fashion, you can have more precise feel of your characters speed and position relative to enemies, which is VERY important when were talking about hand-to-hand combat. But then again, more realistic stuff of course looks more solid.