The reason RP ships lose to PvP ship builders is because they focused on aesthetics, with systems as an afterthought. They lose because they use poorly designed systems, not because interiors make a ship unable to compete.
That's not the correct way to build an RP warship. That's the correct way to build a yacht, which I've only seen two people do. It's better to build functionally with some idea of aesthetics in mind, then work on making it look good. That's how all the successful RP-PVP hybrids have been done.
Even so, if you strip all the hull off these ships and replace the weight with shields, you're probably going to be better off in a fight. It'll last longer before you start taking system damage.
The comparison between a ship with interior and a brick of systems is thus in the old system:
The brick of systems has less overall surface area compared to its system volume, and thus needs less armor, if you even bother putting armor on it. Personally, I wouldn't bother except on the front.
The ship with interior has more overall surface area, so it needs more armor blocks if you want to cover it completely with standard or heavy armor.
This leads to a general trend of decorated ships being primarily tanks, or being poorly shielded. Why? Because in order to decorate ship, you invariably move in the direction of armor/structure tank. The trend strengthens if you look at ships that have a lot of long projections like fins or nacelles, because they have more exterior surface area compared to interior volme. This was a big improvement from the coredrilling era, but it's not as good as it could be.
Stabilizers were an attempt to alleviate the tendency to stuff every possible cubic meter with systems. They failed, instead moving the meta toward ships with one very long dimension. You could argue that this is redundant with the new, smaller systems, but it's really not since people will still try to cram everything together to reduce the number of armor blocks required to cover the ship.
Giving larger box dimensions a practical purpose helps to keep ships from just being a tightly packed mass of systems, but it could also lead to a meta where stabilizers are just little floating blobs a kilometer from the ship. The thing is, even without stabilizers, people can place things in little floating blobs a kilometer from the ship. They just need a separate shield for each one. Rolling the ship would make them very hard to hit. That could get annoying fast.
You could add a chunk-wise moment-of-inertia calculation as a tradeoff for stabilizer distance. Unfortunately that would just lead to the pods being as small as possible with no connection to the main ship. You'd have to connect them with conduits and have severe consequences for destroyed conduits.
That could actually work. You've got a mechanical reason for larger box dimensions compared to your amount of systems, but an equally important reason for connecting the projecting pieces and protecting the projections. Thoughts from the prosecution?
