If an app has only ever supported X11, then it probably doesn’t care about those limitations (the apps that do care probably already have a Wayland version). And if an app doesn’t care about the extra stuff Wayland has to offer, then there’s not really a reason to add the extra support burden of Wayland. As long as they work fine in XWayland, I think a lot of apps won’t switch over until X11 support starts dropping from their toolkit, and they’ll just go straight to Wayland-only.