One's username at a given website can be just as hard to remember as one's password. Many sites reject usernames that are ``already used'' or impose restrictions similar to those of password. Also, different usernames improve security in their own right.
That said, for passwordMaker to remember a username, one must create a custom password and navigate (as I recall) three different screens to insert a username in the username field. This should be a lot easier and more convenient. In particular, could a username field be offerred as an option, but the default password screen?