Cool idea. Perhaps a better idea would be to borrow from the brake balance adjustment in race cars, wherein an adjuster dial/knob allows the driver to alter the balance between the front vs rear brakes when the brakes are applied (very useful in wet vs dry conditions, high-speed vs low-speed sections, etc.). So, instead of adjusting the F-R brake balance, the dial could adjust the regen-vs-mechanical braking, up to the limit of the batteries to accept power input.

Another way of further reducing brake dust might be to have a higher regen setting that dumps excess power to a heat sink and cooling system, up to its limit before engaging the mechanical brake pads/discs.

Pretty much all hybrids already do this, but automatically. When you press the brake pedal, they will command regen first, and only the hydraulic brakes under conditions when regen is not enough.

Series hybrids also have the ability to dump excess power just like you are suggesting as well. Instead of resistor banks (like trains) they often dump energy by using the generator to spin the engine… literally engine braking.

Most of the dynamics like that are abstracted away in EVs (i.e. dumbed down) or buried in menus and not readily accessible. I think this is done in part because the majority of people don't know or care about them, and if they were readily accessible would toggle them unknowingly and be confused or upset. In the Nissan Leaf it was done intentionally to make the car feel as much like a traditional ICE as possible.

In the first gen Nissan Leaf you can toggle between two levels of regeneration by toggling "B mode" which mimics automatic transmission car's behavior in "Hill mode" or when disabling "Overdrive". In the Leaf it just increases regeneration strength when you let off the accelerator. Similarly you can adjust the acceleration curve by disengaging "Eco mode".

Turning Eco mode off and Hill mode on makes the Leaf a lot of fun to drive on winding mountain roads. Unfortunately you only get like 15 minutes of drive time...