In late August 2007, I wrote that I finally got up to one bar in my post count and that I should become a post whore. Seven months later, at a mere 600+ posts, I can honestly say that the post count means nothing to me. Some nights I respond to a bunch of threads, other nights I just browse. I think for the average user, post count is a relatively moot aspect of the site. If you eliminated it, I doubt you would see much difference on a daily basis at all.
On a personal note, as long as people are adding useful or relevant stuff to a particular thread or making new threads that generate some sort of buzz, I see no problem with post counts enabled. I highly doubt it is being abused by more than a handfull of users, however, I have been wrong in the past