Define "almost as much energy". Bike motors aren't super efficient, especially at low RPM's (like when you're coasting to a stop).

A bike has very little rolling resistance, nearly all of the energy used to propel the bike on level ground is going toward fighting air resistance. Even on rolling hills, I rarely use my brakes on the downhill, any regen braking used on the downhill is just going to increase the energy needed to go up the next hill. (and due to less than perfect efficiency, you lose energy on both the regen capture and powering the motor again, so it's a big loss).

So yes, you might recover some small amount of energy used to decelerate the bike at a stop sign, it's not going to be significant percentage of the total power requirements, and you're going to be paying a price in dollars, complexity and weight for this feature.