[perezfan]

I think some collectors (perhaps falsely) assume that pencil is erasable, so it is not as permanent a medium. I think many view ink as being a more stable and long-term representation. I have never had anything written in ink fade, but have sure read lots of stories about it here...

So perhaps pencil isn't so bad... as long as you keep those erasers far away from your prized autos!

Could it also be that many collectors just think that the ink is more visually pleasing and attractive to look at? Seems like an over-simplification, but it may hold true...

Edited to say that Jeff beat me to the point with his more concise post!