u want 3 here goes

1. the masses in general want them

2. They are an essential part to the character that this forum has built up for itself over time.

3. The sig community is a part of this forum, one of the most popular threads in the past month has been the sig request forum, and we had a first round of a sig contest already that had 15 participants and over 100 votes in the first round. To get rid of sigs is to alienate this part of the forums(also why some are so vocal about it)

and another for good measure.
4. I forum looks better and is more personalized with moderately sized and well regulated sigs. which you seem to grant out but deny the possibility of regulating them(thus why its my number 4)