(Email-Backup) is MUCH safer than having it on your hard drive/usb pen and if you encrypt your wallet in a decent way it's totally safe.
Encryption and backup is necessary but quite dangerous for a beginner as your Coins may vaporize if you happen to do a mistake during encryption - backup - restore - decryption.
Thus before encryption and backup of real Coins you may want to do a test run with an empty wallet.
Only if you succeed to restore an encrypted test-wallet from scratch (after deinstalling BitCoin and deleting all existing data), only if you know how to handle the wallet.dat to get it working within a new installed BitCoin program, only then you should start encrypting your a real wallet.
By the way, I think it would be a good idea for BitCoin developers to create an automatic backup/restore feature that can be used not only by freaks who know how to move files but by normal people too.