When the user of the Android Wallet wants to do a backup he has to give a password otherwise the application won't do the backup. Should the application really force the user to give a password? I mean one of the biggest security risks when it comes to losing bitcoins is in my opinion forgotten passwords. Why not make it optional.
Why? It is easy.
If you wont put a password your backup keys are so easy to be taken by someone and you might loose your bits.
So.
Password is most important thing when you do a backup