Steem wallet needs more security. When a user makes a transaction, there must be a confirmation with phone because current wallet can any one use it if he has a password. So, if developers provide this option, there will be more security. So that time no one can send steem or SD to account without code confirmation such as steemit new registration method.
Password is private key. Multi sign would make us money transmitter in some jurisdictions.
Don't worry, we are working on robust solutions.