I disagree with having a variable regen paddle. It's just another thing that will untrain you from relying on the standard brake pedal. Think about it, if regen cuts out when you lose traction or if you're in N, you're screwed. Better to stick with muscle memory and have variable braking done with the brake pedal. It's accomplishing the same regen. You just are less likely to maximize regen and transition to friction braking at some point. Sure it's some brake wear, but at least you'll definitely stop the harder you mash that brake pedal.
Don't get me wrong, I still love using the regen paddle. I just make sure to lightly press on the brake pedal to ensure should a panic stop be required, my foot is already on the brake and muscle memory (and ABS) can take over.
Now, if you're talking about a programmable preset regen amount for the paddle (low/mid/high) that's still on/off in behavior, then I can get behind that.