The post count is a very inaccurate, but still effective way to show how much you contributed to the forum.
If you wrote thousands of posts, you want a little trophy. It's not shallow, it's human.
We are not all Buddha's or Jesus's.

Plus it helps to tell the credibility of the posts. Again this is very inaccurate, but it can tell you something. In most cases posts of people with higher post counts and older join dates will be more reliable.

Also, I think it's fine that there is a bit of a status thing in the community. It makes things more interesting. It adds drama. If you don't know what I mean I can think a little and write examples of what I'm talking about.