Just to clarify, the post count is not a replacement for karma. I'm still thinking about a replacement for karma points, an indicator of a Pinsiders "reputation". I wanted to get rid of karma first, instead of directly replacing it with something else. And frankly, I'm not completely sure yet what it will look like. I'll open a topic for brainstorming this with the community at a later time.
Note that the post count also acts as a direct shortcut link to someone's latest activity!