I feel a major problem with modern Smash is that the devs seemingly chose not to immerse themselves in the games' worlds, but just the games themselves. There's a ton of meta UI/game mechanic references in fighters that make it seem like they're just trying to represent an entire game instead of the character themselves, while Namco-era stages based on modern games are, with rare exceptions, just copy-and-pasted from the original game graphically without any creative liberties other than layout. Kinda throws me out of the whimsy and fun when I'm playing not as Sora, but as an anthropomorphised Kingdom Hearts. Also makes it hard to extend these series' representation further, how do you do Bass or Roll when all things Mega Man are inside one stage and fighter?
Where's Sheik? She's the only revealed fighter not shown there. Every other Melee character was an unlockable or Zelda