I think pseudonyms might have the same problem that too much customization over myspace profiles drove people to facebook; people are stupid and don't do what is best for them. More customization of profiles has probably been the #1 request on facebook since it's inception and they have deliberately not launched it, which ends up being what the people actually want despite what they think they want.

Everyone wants to be able to set their profile to their favorite color and have their favorite song autoplay, but no one wants to see other peoples crappy color schemes or hear their music that you don't like. Lots of people want to have some random name on Google+ but people don't want to interact with a bunch of people named "vagtastic" or "bluntzzz".