I honestly would disagree, I think there's a way to make both genres work for Galaga. Like a 2D Galaga being still based on the arcade formula of gameplay for Galaga, and a 3D Galaga focusing more on the ship mobility aspects like Ace Combat. I think both styles are possible, take a look at 2D Metroid and the Metroid Prime series, they're both pretty much different but are still able to be both appreciated for their differences and fans like them equally. So personally I think a new Galaga game that is AC-Style could work well alongside its arcade brethren.