I've been wondering about that too. The chances that version 1.0 got it all exactly right is less than perfect. The SolidCoin fork has some interesting criticisms of Bitcoin:
http://solidcoin.info/faq.php
Still some calibration and iteration for Bitcoin to do as new lessons are learned about P2P currency. But the Bitcoin protocol and implementation are under active development, so I wonder to what extent it can still evolve without a reboot.