A nice idea, TCD, but that only affects MY empire, not the structure of NPRs.
I would love to have the option of a "sunless sea", an area with starless nexii, relatively short distances between warp points, that act like relatively open seas that are difficult for any empire to claim, that are routes for trade, piracy and conflict.
Heck, how about an option that habitable systems have few warp points, but almost always connect to starless nexii that have lots of warp points? That makes habitable systems more defensible, but ensures they have more expansion options once they get out of their system. Yes, you end up with a lot of unimportant systems, and yes the map can be cluttered, but part of the fun for me is arranging the map.