I've used left-foot-braking in my (ICE-powered) daily driver for years.
Regenerative braking is very different to taking your foot off the accelerator in a conventional ICE car, it's much more powerful a stopping force than traditional engine-braking.
I understand the rationale for moving the pedal to illustrate the amount of "braking" force. I'll admit I'm not exactly a typical driver though.
Why not move the gas pedal too, when using cruise control then?
If you push the gas pedal, you'd expect to go faster, wouldn't you?
They used to, but not by design. Back when throttles were still cabled I could feel the cruise control doing its thing by lightly resting on the pedal.