To this day I have yet to meet a single person who has played Melee that has found it "too difficult". Most of my friends are actually casual players of the series, and although they move on happily from sequel to sequel because of new characters and features, every single one of them says movement in Melee has felt the most comfortable and precise. None of them utilize any advanced techniques, in fact, most of them don't even know about them.
Sakurai's stubbornness to give the game the physics and movement it deserves is a total mystery. If it's all designed for casual players, then why don't they just ask them about it? The general gamer that will play the game is not unreachable, but Sakurai sure seems to be.