Yes, it's weird that the Politburo consists of only two members. I'll be introducing an amendment to the bylaws shortly that will include five Regional Secretaries in the Politburo.
We had Regional Coordinators as an unofficial position under Section V.1.f. for a while, but it fell apart due to lack of interest. When I wrote up the original by-laws a couple years ago, my goal was to try to keep things simple and allow for flexibility, but having more regional representation would not be an awful idea.