I guess I just don't understand this conversation. I thought the way it worked is the brake pedal called for increasing levels of regen braking up to a point, beyond which the friction brakes are applied. The brake lights come on whenever the brake pedal is applied, as the implication is that the driver is slowing or stopping. B mode applies regen braking to control vehicle speed on a long downgrade, and is not intended for slowing the vehicle in normal circumstances. The implication of B mode isn't that the vehicle is slowing, just controlling its speed, so brake lights should not come on. And when you don't have your foot on either pedal, power is neither applied nor drawn from the motor/generator, so the car just gradually slows from internal friction, rolling resistance, and wind resistance.
Other than making B mode variable, which would be nice but a rarely used feature for most, I don't see how that could be improved.
White 2012 SV delivered 10 Dec 2011 returned 25 Nov 2014 replaced with stopgap ICE Sentra
[35 months] [35K miles] [9 Bars]
2013 Volt replaced after 36 months/30k miles with ICE Rogue
2016 SV-adjacent May 2016 lost 4th bar March 2018