Hichigo's power probably is only due to the fact he isn't as naive and hesitant a fool as Ichigo. We have learned a long time ago that a zanpakutou only cuts when the hand that wields it wants to cut. Ichigo, being a far too typical shounen hero, almost never wants to cut anybody and thus he rarely can. If he had a healthy attitude like Kenpachi, he would kick ass in shikai already and major ass in bankai. Vaizard mode would make him unstoppable.

But alas this is no Kaze no Stigma so we have no chances of Ichigo ever gaining an attitude suitable for a man carrying a sword.