I am yet to truly discover why they have them on a guitar haha! Purely there for decorative purposes on all of mine.

Had a jap Strat copy that was hot rodded and it ended up with vol for each pickup and 3 on-off-on DPDT mini switches to switch on each PUP independently. Didn't see a need for tone controls 40 odd years ago, even on a Strat, and barely touched them since.