[schoen]

Shouldn't the resistor having to end up dissipating exactly as much heat as the friction brakes do, by conservation of energy? Is there a reason that it's inherently mechanically harder for the resistor to dissipate that heat?

[leetcrew]

not really, but you have to have the friction brakes anyway, so why add more parts?

[ohazi]

Disks and pads wear out. I haven't done the math, but I assume you could put in a big (wine bottle sized?) power resistor that can take the thermal cycling more or less indefinitely.

You'd have to cool it, as other commenters have pointed out (you're putting a car's worth of kinetic energy into the thing, after all). I'm not suggesting that it's a good idea, just possible.