There is no real reason to go back for several reasons.

I'm already in a stable relationship.

I've got no urge to boost my ego (or whatever) by trying to get more and more friends listed. The person who connected me has 84 friends. Without trying, I have three. *twirls finger*

Coming up with non-retarded testimonials is hard.

Friendster the site gets really slow sometimes.

It is kind of cool seeing pictures of people of whom I only know of by name or by IM/email/whatever. Also, it appears I'm only four hops away from Rands.

What is friendster going to offer? Dating services? Don't need it. Blogging? Hurf, I could use slashdot or set up something myself. (I'm not the target blog audience, obviously.) Community/group chat? That could be enticing depending on how they pull it off, but how much time am I going to want to spend doing that? What's to stop me from meeting interesting people and then use IM/email?

Where's the money in it for friendster?