A real problem of most advanced bases and current idea of VC vault rooms is absence ergonomics.
Lookt at Vault Base. I know that it is on bad place, not ideal for PVP. And all of us know (hope devs too), that PVP activities need a lot of stuff, you have to put somewhere stuff and take fast, if is needed. So Vault base fails from ergonomics, because you have to walk a lot to get inside. So i can guarantee, if Vault Base would be relocated somewhere near PVP cities, if Vault Base would be more cheaper (even first base in base hierarchy), most factions would put all stuff outside the vault on ground and inside areas would be used as common crafting material resources and few hi tech items storage.
In TLA or Requiem, there exists already solution for this. 2 types of accesses and exits. One long, thru surface place (similar like outside area in VBase), second, for members, direct enter and exit in or out the base to world map. Of course, that direct access leads directly into place with a lot of cabinets and other storages.
So idea that you can buy your own room in VC, but you would need to travel across 4 maps (suburb, inner city, vault surface level and finaly vault underground level) two times (in and back) is, ehm...you know.