Some additional thoughts/informations:

1) recovery phrase like the electrum does as greg mentioned (~bip39) in case you have lost your wallet (encrypted or unencrypted) requires a bip32 hd wallet: at the moment not supported by bitcoin core.

2) Current bitcoin-core always creates a unencrypted wallet at first start. If one decides to encrypt the wallet, all used private keys (`getnewaddress`, change addresses) where exposed plaintext over the wallet.dat file during the time between creation and encryption.

3) An encrypted wallet is basically not an encrypted wallet. Only private keys are encrypted. Public keys, wallet transactions, labels & comments are plaintext stored in wallet.dat.