You may be giving him too much credit. Surely he has a team of animators and programmers working on it, right? Regardless, the Smash developers are in it for the money. Your money is your thanks.
It is a giant key, not a sword. And using a giant key with a Mickey Mouse key chain as weapon is far from generic.
Depends. Sora originates from Kingdom Hearts, which is a video game franchise. So Sora himself originates from a video game franchise. But of course, Kingdom Hearts is also a cross over with many other Disney franchises, most of which orignate from outside video games. And Sora's keyblade does have the Mickey Mouse keychain.
We had iffy things like this before, Shadow Ball, Ho-Oh, the Pokémon's voices, and Ash Greninja all originate from the anime. Personally I consider the rule to not be broken but because factually it is not broken; Sora originates from a video game franchise.
Though I hope that the rule will get properly broken sometime, restricting the roster to "celebrate video games" is the lamest way to celebrate I have ever seen. Since when are celebrations about restrictions instead of about fun? Do you also fast on your anniversaries?
No kidding, sometimes I literally confuse some Fire Emblem characters with other Fire Emblem characters at the start of the match, learning only a few seconds in that I am fighting against Corrin or Byleth instead of Byleth or Corrin, respectively.
Pyra and Mythra are as generic "anime" sword users as a generic "anime" sword user can be. Liking them really undermines your rant about generic "anime" sword users.