That is another reason why regenerative braking should be integrated with friction braking on the brake pedal. If so, when regen is less available and regen and friction are on the brake pedal, then pressing the brake pedal harder will simply engage more friction braking for you. I.e., it does the right thing, even when regen is less available.
I'd still like a big resistor so we can have dynamic braking when the battery's full. No need to wear out the brake pads.