It would be nice if bitcoin would auto encrypt wallet file based on a password, which you enter every time you open bitcoin client.
but thats the problem. its not "bitcoin"'s responsibility to encrypt wallets. bitcoin is only a network for moving btc between two accounts. its the users that need to be secure about their usage. it might be nice if the apps that connect to bitcoin start to offer certain protections, but the users are the first line of defense: unique passwords everywhere, encrypted and backedup wallets and smarter, safer browsing