From WoWWiki

Benefits of having your own account

• You can add pages to your watch list, which works like a bookmark list, but one that also instantly reports changes to the watched pages!

• You get to have your own user page where you get to tell the rest of the community about yourself. If you like.

• People can drop comments to you in your talk page!

• You automatically get a list of your contributions (and can show it off to others if you like!)

• You can change how WoWWiki looks to you, either by selecting from a pre-set list of skins, or even uploading your own!

Drawbacks of having your own account

Well, none that any of us are aware of.

Having an account at WoWWiki doesn't mean that you're suddenly exposed to the world.   – You can tell us as much or as little about yourself as you like.

Oh, wait, I just thought of one:

• You get to find out how much fun it is to edit pages together with other people. It can easily end up taking more of your time than you originally thought it would!

→ I'm sold! Sign me up already!