>we won't be using the advanced ship-building rules or ship battles as detailed in Book 2
Basically that. There's still plenty of SPAAAAAAAAACE, and I may eventually give the group a ship of their own, but it's intent is to be a setpiece. Things like the orbital bombardment, teleportarium, etc. make me have to either plan out alternatives, or start waving technobabble nonsense around.
Also ship combat, if you're not an officer (i.e. somebody with appropriate skills or classes) or captain of your own ship, can get really, really boring, and I am under the impression that would only get worse in a pbp setting.