Re: Generate username (+ blog url) from fullname
This is a nice and succinct accounting of what you are trying to achieve. Parsing a registrants first and last names from the BP “Full Name” field and then using that as the username would be a nice option.
But I’m not too sure whether you can remove–or hide as would actually be the case–WPMU’s username field from the registration form. WPMU is the underlying foundation of the system. It controls everything. With enough coding, I’m sure it would be possible–but not that sure on the practicality of doing it.
As I had suggested before, I would head on over to the WPMU forums and post a similar thread since this deals with hijacking, altering, and superseding WPMU’s registration protocols. That way, you will hopefully get some feedback on both fronts and find a possible, acceptable solution.