Why should I use my real name?
Using your real name is important to the Wiki community. First, and foremost, it gives you instant credibility, because you're standing behind your edits with your reputation.
However, using your real name alone doesn't give one credibility; you must also make valuable contributions rather than just talk trash.
Fundamentally, the question is one of community. Would you introduce yourself to your next door neighbor with a fake name? Probably not... and the people on the wiki are your neighbors.
However, you may want to consider that this is an online community, and not quite the same as your geographic neighborhood. One approach is to never post anything you wouldn't want associated with your name. Be warned any of your comments (whether positive or negative) may be remembered by local businesses and restaurants, and anyone around the world with internet access (note: not a 'next door neighbor') can read or find out about them. Putting material on the wiki should be considered an act of publishing, in a sense.
Many people have created fake or dubious pseudonyms just to troll or trash talk a single restaurant, business, or individual. This type of cowardly behavior is not constructive and is unfair to the recipient of the complaint. Wiki edits should be fair enough that you'd be willing to say them to someone face to face. That's true whether or not you use your real name, but it's certainly easier to be unfair when you hide behind a pseudonym.
What if I want to use my real name but don't want to get picked up by Google?
An alternative is to use a slight modification of your real name (e.g., instead of FirstLast, you'd use FLast, FirstL, RealLifeNickName, etc.) and indicating so on your user page. That way, you still establish credibility, and you can always remove the link to your real name after you've confirmed your credibility through your constructive edits. This option is good for people looking to evade Google. The point is accountability: establishing a reputation on the wiki. Of course, you might wind up making friends who wind up only knowing you by the name you use, so be aware it may well become your new nickname in some circles.
When is it ok to use a complete pseudonym?
It is ok to use a pseudonym if you are known widely by that name. JabberWokky, one of the Davis Wiki's most prolific and respected contributors, sometimes goes by JabberWokky in real life. He also makes his real name available to anyone who is curious.
Other users who choose to use a pseudonym to remain anonymous manage to establish their credibility through making a history of providing many valuable contributions to the wiki. (For example, by creating and editing pages on an on-topic subject that the site is currently lacking. The anonymous AlphaDog did this with the Davis Wiki's Town Flora section.) However, using a pseudonym only grants one a certain degree of privacy, because the IP Addresses of all editors are publicly logged.
I'd like to change my user account to my real name
You can do this quite easily, although as you'll see, you're basically just closing down the first account and signing up again:
Click on 'settings' in the upper right hand corner of this page.
Change your email address to a junk one.
Save your settings.
Click on 'settings' again.
Click "Disable this account forever".
Click 'new user' in the upper right corner.
Signup with your real name.