Right, you beat me to it. Captial requirements are there to prevent banks from going insolvent. Reserve requirements are there to prevent the money supply from spiraling out of control. These are completely different objectives.
Thanks for pointing this out. Our problem now is that even with reserve requirements, banks can use securitization to expand the money supply infinitely: http://arxiv.org/abs/0904.1426 . Reserve requirement aren't normally the binding constraints on banks, but they might have helped prevent some pathological situations in the past. The rise of shadow banking has shown that they are no longer a sufficient constraint.