I have a signature and Yes I think there should be more of a limit on them.
I support people in making their posts more creative and more fun by the use of signatures. I just wish that some posters were a bit more conscientious about signature length.
I really don't like whole screen fulls of signatures: laundry lists of when you were at WDW all one trip to a line, whole songs that go on forever, 2 pieces of clip art 5 countdowns and a couple smilies all thrown together. If it takes me more than 2 page downs to get past a signature to the next post, then I think it's too long!
I really enjoy reading most people's signatures and seeing their clip art, so turning off the signatures is really not an option for me. I just grit through my teeth and {page down}, {page down}, {page down}.