I think another aspect to this is that a lot of games aren’t “one and done” release it and move on any more. Big titles can get supported, changed and added to for years, and if you’re doing multiple UIs for each mode of input that means more work each time.

Plus if you allow players to swap what they use in the middle of a game, going from mouse+keys to/from joypad (on PC, but can also be done on console) then you’ve got to handle that in the UI, mirroring the same state in both of them as you switch without error/jank, and that’s a lot easier the more they have in common. If someone nudges the mouse and the UI refreshes back to the base menu, resets all they did or they lose their place, people will moan too.