The problem of forgotten passwords
For existing wallets the Mnemonic can be found in [Account Settings].
This worries me a little bit. If I leave my computer while logged in (a stupid thing to do, I know) or if someone distract me on purpose, he can read off my password from that page. I assume the mnemonic is created client-side, so it must be able to find the algorithm in the javascript, and inverse it.
If you don't record the Mnemonic or make a paper backup and forget the password there is nothing we can do to help, the coins are lost.
What is the difference between writing down the mnemonic and just writing down the password?
I am not sure if there is a better way to do it - it is a balance between loosing coins through being hacked or loosing them by forgetting the password, some compromise has to be made. But password recovery always makes me uneasy - if my password can be recovered by me, it can in principle be recovered by somebody else.