Even though you do the work, so my vote shouldn't really count (Do I know how to suck- up, what? :) ) I have to agree with you. I have too many diverse interests to want to see a fractionation of the list; and where would it stop?
I know; I would get pings for each fraction, BUT, I would not have the convenience of knowing that I would not miss a ping to an interesting article, because I had neglected to sign up with the proper sub-list.
That sums it up nicely.