I recently put a password on my admin user (and frankly all users) because I am often mixing a wedding band and may be mixing from an iPad out in the crowd. That leaves the mixer unattended, so locking it from kids (or the full sized drunk ones) is a good idea.
However, that means that every time I turn off the iPad and the app disconnects, I have to reenter the password for my user. Having the ability to save credentials for quick reconnects would make the process a bit less scary as in a panic situation, it saves a few steps. And, since I have Face ID to secure the iPad itself, this negates the security loss of storing credentials.