Actually, this isn't the worst idea. It can be hard to tell what kind of input device the player's using, especially on PC. Are you using kb+m, xbox controller, psx controller, generic bargain bin controller, etc? Also you can't just assume that because a controller's connected the player is going to use it (and lots of games do... much to my dismay since they make me go disconnect the controller). Once the player presses at least one button you can tailor all the inputs to that thing.
Newer games simply switch active input devices on the fly by using the input scheme of the last pressed button. For example, if you're using WASD but then press A on an Xbox controller, the engine automatically and quickly switches to that input
GTAV was great for that, I could use KB+M for shooting and stuff, then switch to a controller for driving/flying, which is much easier with analog inputs
And you couldn't do that by just interacting the the menu itself? Come on mate, plenty of games switch it on the fly.
