We’ve heard plenty of things like, “even without motions, they’re just going to get frustrated with losing and find some other excuse”, as well as just a general sentiment that Street Fighter wouldn’t be Street Fighter if you got rid of motions (despite the existence of Ed and Falke), or that it would be too difficult to balance without them.
While there are a non-zero number of people who definitely do just find some other excuse for losing, I think we’ve seen demonstrably that it opened this game up to people who hadn’t been playing fighting games before. We’ve seen that Street Fighter is still Street Fighter without motions. And we’ve seen the game balanced, even with the new controls versus the old, just with a 20% damage penalty to moves that typically used motions; it’s such a non-issue that you rarely come across modern control players at the higher ranks at all.
This is not a petition to remove motion controls from fighting games forever, but I think it shows how unnecessary they are to making a good fighting game if you’re not bound by the legacy of your franchise. It’s also why I think you’d have to be crazy if you’re making a brand new fighting game (like Project L) with motions when you don’t have to, unless it’s somehow super important to your vision for the game, as it’s just going to limit your audience.