Configuration->Minimum Values->E-Mail Address: Why is this there?

I was reviewing the create_account/create-address processes to try and streamline the "required fields" settings and came to question why the subject configuration setting is even there:

1. The email address value is the customer's "key" to their account -- why would you make it optional by allowing the minimum length to be set to 0?
2. The email address is being checked (over and above the minimum length value) to ensure that it's a valid email address which seems to "trump" the minimum length setting anyway.
   To repeat this post's subject line: What purpose does Configuration->Minimum Values->E-Mail Address serve?

If the answer's "None", I'd like to suggest deprecating and removing it in a future release.