It is mostly because he can't take much damage, flinches, switches sides and his moveset was ported from a 3D game and it can't work in 2.5D game. He also is a lot bigger than he was in Other M and you can hit him anywhere, which makes him even more pathetic.
Even for those who played Brawl without knowing anyone except for few characters and then tested that unpolished piece of...something would feel how much worse it is.
Anyway, i rediced to remake dodging animations because they were just animations from previous versions recreated with this model. Here they are:
Covers a lot of distance in small amount of time, but they are still laggy and invincibility frames don't last for too long.