Re: How to use full name, first name + last name
Fact is, that BuddyPress can still only build off of the weaknesses of WordPress itself. What you’re trying to do can really only be worked around with smoke and mirrors, because WordPress itself doesn’t really care what your real name is; the fields exist simply to add depth to a username.
Short of developing your own MU/BP plugin to shift the emphasis, you’re out of luck. Usernames are 100% necessary, because it’s how you login and out of the site, along with your password. Usernames cannot include characters other than alpha-numeric, so you can’t use an email address either. This means they MUST create a username. You could make a plugin or modify your registration to force the creation of a username based on two fields (first name + last name) but that means you’ll need to tell the user what your website made their login name to be, instead of letting them make their own.
There really are only a hand-full of sites that don’t use some kind of username as a login, and in my opinion it makes more sense because not everyone uses the same email address for life, and what happens if I registered with my work email address and get laid off, and I need to login but forgot my password? Now my new password goes to an email address I have no access to. In this case, username makes the most sense, and is almost fail safe unless you’re REALLY having a bad day and forgot your username too.
What about people like me, that like to use their middle names? I get no respect I tell ya! 
