I ride a bionx and I love the braking feature of the regen. Without it, my brakes wear out faster and I have to squeeze harder to get the same braking effect. Not only do I save the time and money from changing my brake pads more often, I save the rims on my wheels. If you commute in the rain, you can wear out your rims much faster.
Of course, the energy I get back every time I stop is an added bonus. Any time I need to slow down, I actually start my braking earlier so I can maximize the regen.
I feel safer with regen. The regen braking isn't affected by the rain. And when I'm going down on a long steep hill, instead of blasting down at 40mph, I can enjoy the downhill at 30mph without heating up the brakes.