The reason for electric WP is fuel economy. Same with alternator clutch that disengage when batt condition is considered good, thus creating batt undercharge for many who don't drive long distance.
All of these unheard off until fuel cost sky-rocket and feds impose tax/penalty on car mfg when their fleet avg doesn't meet requirements.
Latest BMW feature is shutting off engine (on non hybrid) at stop, then when you switch your right foot from brake to gas, the engine starts again. Sounds like alot of work implementing this feature (especially considering safety on situation of turning left to cross oncoming traffic) but emission and fuel saving dictates at the end.