About five years ago, I switched my online accounts to my real name. I used to go by OoklaTheMok on forums from Ars Technica (where I still use it; it's the last vestige of that nickname) to AnimeOnDVD. Then I started working at TOKYOPOP and it seemed more useful to go by my real name because that's what appears in my credits. I'm happy with my decision and it has served me well.
But if I had some other name that was more uniquely mine, instead of just calling myself after the name of my favorite band, I would have been more likely to stick with it. Or if I myself were the musical artist(s) known as Ookla the Mok. As it was, people in a couple different communities were thrown for a loop when I started using my real name instead of the nickname.
So anyway, I like using my real name. But that doesn't mean that's a good choice for everyone. Google+'s real names policy is a stinker. There are a multitude of very valid reasons for using a pseudonym (others have covered them extensively, so I'll not do so here), and if Google+ doesn't accept them, it is going to wither away as another failed experiment.