It's worth noting that not all "Hanmi" is the same anyway. So pointing out -a- particular hanmi is more exact. That said, beyond its use to make your "martial art" more uniform,(and lets face it, we all have to do that to one degree or another in our arts) I can make a case for it being practically useless to even being detrimental to stability in actual combative movement.
What kind of hanmi did Osensei teach in Iwama? Where did he get them from and what do they do?