Cryptic why not just lose the instancing and sector space and tie all the planets togeather. It would really give this game such a awsome feel, I would love flying around and passing planets as i go, maybe stoping to kill some orions i meet on the way etc. You can make bases and ships respawnable in the respected area for what ever mission is tied there. Sure flying from ds9 to sol mite take 15min at max impolse but that dont bother me at all. This would also give the game a better community feel, Kill 3 birds with one stone. Also with this system in place we can have open pvp
Two words: server stability.
We have issues NOW, with instancing. If everyone who was in Earth Spacedock (or Sol System, or DS9) was in the same instance, lag would be rampant (which it already is; it would be even WORSE).
I doubt this engine could handle such large zones and not everyone wants open PvP.
It has nothing to do with the game Engine. STO has a huge graphic footprint because they were intentionally going for something of a higher visual quality. WoW can get a way with Phasing because of its low system requirements. If STO had phasing only the high-end machines would be able to play it. Everyone else would just lag-out, specially when their computer system was tryign to preload the next zone. For the game to be viable for lower-end systems some compromises needed to be made.