Any module for this?

This is just driving me crazy. How come there is no API or module to automate user creation?

All I need is create automatically a member account when I supply a username. The closest I found is the Auto Register module in Devot EE but this is actually not what I want exactly. It creates an account when someone tries to log in with a non existing email account. That sounds very scary, I cannot imagine if someone tries a brute force scan on a a website and it creates an account for each try…

What I want is able to pass a username to a template or module somehow and EE will then create the account for me. I searched for hours and it seems there is no way to automate the user creation in anyway with Expression Engine. There is an auto log in module which works nicely but I want a auto account creation module in a similar way.

Does someone found a solution to this or had a similar requirement?