I drive an electric van at work, I keep the regen on max because I’m lazy and it saves me some braking and some power - but I still need to use the brake pedal! Regen is fine if the speed of the traffic slows, but if you want to actually stop, or stop faster, you need the brake. Regen won’t make fuck all difference when a kid on a bike wobbles into your path. I’m sure they could increase it, but enough to rapidly stop a heavy vehicle going downhill? I dunno.

Edit - also, it’s intermittent if the van decides it’s having a bad day.