Just the email is fine. It serves a couple of purposes. Whenever you trade/sell/buy something you can have forum members simply click on your name, and the menu provides an email option. Your email is kept confidential, unless you reply via your email address. The other benefit is that you do not need to post your email address in public. Some people don't like broadcasting that information, others don't care.
I some cases a nonmember replied to an inquiry on an item in a thread with a published email. Long story short, the deal went bad and we couldn't do much to help that person since it was a deal that didn't occur between two forum members, rather one member and one omplete stranger. The guy ended up with a high dollar knife and nothing to show for it.