Well, I do care where Zalbaar fits into this because:
1. He plays a major role in the first game - Kashyyyk is probably the only planet where you *have* to complete a side quest of one of your party members regardless of whether you want it or not. In fact I think that without Zalbaar as a party member you cannot complete Kashyyyk.
2. Kreia mentions that Revan went there alone and everything that's connected to Revan's fate is of interest to me (and I believe to all of the ones who are impatiently waiting for K3).
3. Strangely enough I consider Zalbaar to be one of the characters in the game that shows signs of development and has a temperament allowing change - example is when he defies Revan's order to attack Mission in the DS scenario - and that means that he posesses something that most of the Wookies don't - a will to go against the most ancient and sacred of all traditions (a life debt).
4. He is maybe the only character that remains a mystery to the player throughout the entire game because of the limited pool of dialogue options and of course Zalbaar's origin as well as his mentality. If you're a problem solver (like me) then he would definitely appeal to you.
I think that's about enough reasons to be interested in Zalbaar.
Thank you all for the wonderful speculation and the variety of opinions this thread managed to gather. If anyone has anything different than those, of course he/she is welcome to post it and it would be well appreciated. As for me, I personally believe that the developers left a hidden door for further use if need be.