HubKarma is a score that reflects the degree to which you link to others' Hubs and to Topic pages in your own Hubs. Linking to relevant, high quality Hubs and Topic pages can improve your reader's experience. You can easily do so using our Linking Tool. HubKarma has some influence on your Hubber Score and is on a 0-100 scale.
I took this right off the help page here at HubPages.
OK, so it has influence on our score, initially this may be true, but more practically I believe it is a tool to promote HubPages and the corporations that stand to gain $.