I feel like by your logic, most modern platform fighters are just copying Melee. Rivals of Aether? Just another half-assed Melee clone. Nevermind the unique mechanics, nuanced movement differences, and overhauled recovery system, it has wavedashing and one of the characters is basically Marth, so CLEARLY they were trying too hard to pander to fans of a game you don't play instead of forging a unique identity. (Of course none of this is true because Rivals has some of the most unique characters and gameplay in the entire genre, which I really think could be said for NASB as well.)
At this point mate, I'm starting to think you just hate wavedashing. Which is fine, you can stick to Ultimate, the only modern platform fighter that refuses to incorporate wavedashing in any form.
Wavedashing came out of airdashing, though... unless the devs decided to tack a ton of landing lag frames onto the airdash for some weird reason, wavedashing was gonna be in the game no matter what. Do you really want the devs to make the game feel worse just so it
doesn't have wavedashing in it? (I mean, that's exactly what Ultimate does, so I guess I shouldn't be surprised if that's the case.)
Either way, people don't hate on NASB because it has wavedashing in it, nor for being too derivative of Smash to begin with. If anything, they hated it for not mimicking the volume of content and polish of Smash to a T at launch. NASB got backlash for how it TRIED to stand out from Smash, not for playing things too safe or pandering to Hbox or whatever.
I think there are a few very important common factors between MVS and Brawlhalla that you might not be accounting for here. Think pricing and brand appeal, and I think you'll realize why those games have such high playercounts compared to every other non-Smash platform fighter.