I think users should have a signature either at the end of a message or under their armatar. Some other forum sites have that and I think it's creative.
Meh. I personally hate signatures. I really don't like them. Often, they are as big as the actual post. But it looks like a lot of people like them, since a lot of forums have them, so, I wouldn't be surprised if they will add them in the next version of the site.
It's really useless seeing that your username is next to the post. There's no need for an automatic signature to be put into AG3 when you can do it yourself.
I'm guessing the idea is that you could have like your own quote or something on every post you make, not just your name. Besides, if you're going to have signature, whats the point of writing it out every time?
Signatures would be completely unnecessary, if people can't tilt their head 1° to the left, then there is something seriously wrong with them. Sure, they might be a little cool to have them, but it just takes up space in the post and makes each page longer which is just really annoying.