With Jami, you are not forced to have a password on your account. Don’t worry, it’s a decentralized system, consequences are not the same than on other systems.
With a centralized system, you use your password to authenticate on a public server. Someone who knows your password can usurp your identity.
With Jami, your account is stored in a folder on your device. The password is only used to protect you from someone who have a physical access to your device by encrypting the account’s archive (and don’t let anyone access your private key)
If your device is encrypted, you may not want/need to use a password.
Note that if you forget your password, there is not way to recover it.