Encryption is not some magic dust you sprinkle on an application and it magically becomes secure. If you can come up with a wallet encryption scheme that has more upsides than downsides, there's a good chance it will be implemented.

IMO, that's just inviting disaster. The client should only be running on machines that are inherently secure. Doing this will encourage people to run the client on insecure machines, which will compromise their wallets even if they are encrypted. Strong passwords will be forgotten, leading to lost BitCoins. Weak passwords will be brute forced, accomplishing nothing.