Okay, well good for you, but I don't feel like letting complete strangers know EVERY SINGLE THING about me.
Plus, I have usernames that are based off of stuff I'm into at the time. For instance, anyone who has read the Codex Alera series would know that Fidelias (IS THE MOST AWESOMEST CHARACTER EVER) is from that series. So it's obvious that I not only read the series, but also loved it enough to use it as my online name.
Plus, how is it more responsible that you use your real name? I mean, the only thing that affects is that now someone can take a 3 hour trip to your house to harm you.
To the rest of us who are normal, what do we care? Your name could be "Fuzzymcnuzzlepuffs" and it would carry the same amount of weight.