I wasn't thinking so much about having a the HUD/UI be configurable from a coding standpoint, but rather have it generic enough that with a table and the associated graphics, you define what the HUD(s) and/or UI screens look like. (I might be misinterpreting your post, BTW).
That way if someone wants to do FS2 graphics at 1600x1200 and play it on their 35-inch plasma display, they can. Or on a Palm Pilot
TC projects could have their own UI and HUD (think about the differences between FS1 and FS2, now image Star Wars or Babylon 5, or Ender's Game or whatever) And a full campaign (with no Volition ships, weapons, sounds, music, UI, etc.) could be freely distributable, w/ no licensing restrictions -- you can't
legally distribute the FS2 VP files, although they are required to run fs2_open.