This is a feature of Bitcoin, not a flaw. You MUST have your private key to access your coins.
Sure, that the bitcoins are safely stored on the block chain is a feature. Having to at the same time store private keys, on the other hand, is a major flaw not a feature.
And in the future if people will in practice in most cases let banks keep their bitcoins safe we are back into the old money paradigm again.
For Bitcoin to become more than a tool for investments this problem needs to be solved in better ways than forcing people to manage their security themselves or outsource the security to a third party. The whole idea of Bitcoin is to move away from the trust paradigm. It should be possible to trust the Bitcoin system instead of having to trust oneself or third parties.