Not necessary, but for additional privacy.  If the BTC address is also encrypted then that would prevent an unauthorized individual from being able to see how many BTC I have in that address or viewing the transaction history for that address.

Thanks for providing the link.  The encrypted wallet described in that thread is exactly what I'm looking for.  However, when I go to bitaddress.org the text field to enter a passphrase does not appear and I don't seem to have the option to create a paper wallet with a blue background and an encrypted private key.  Is it just not up and running yet or am I missing something?