Which sort of makes sense in the best-of-all-worlds interpretation of the ship:
- The low registry establishes her as an old design, now surplus to requirement.
- The impressive size reveals the original mission for the design (my pick is "shuttlecarrier", as per some old fan interpretations of the McQuarrie designs, but "transport" or "factory ship" or "hospital ship" etc. are also available).
- Come Burnham's War, Starfleet dusts off its surplus ships and turns some into flying laboratories for research on miracle weapons; ships with lots of internal volume are handy in this respect, especially the big ones with dual warp cores of which only one is needed for flying if speed isn't an issue, so a couple of Crossfields get chosen.
- To keep her from being hopelessly antiquated, Starfleet bolts on semi-modern warp nacelles. It also installs spinners on the primary hull for bleeding off the energies (and other qualities subject to conservation laws) generated by the doodads of the cackling mad scientists.
- The vast interior is then fitted with the assorted modular facilities (often of weird dimensions) the various venues of research require, with corridors and turborails erected willy-nilly between them.
- Of the old volume, only the very aftmost tip of the shuttle facilities is retained, its floor nicely polished now that it becomes the sole shuttlebay. It also gets swamped with logistics when the original routes get blocked by the silly labs. But its archaic fighter deployment system on the lower deck sees use eventually, surprisingly enough.
- Once the spore drive pans out as a war winner (not least because that's how Lorca spins it), the other experiments are expelled, along with the respective researchers and the S31 guards who kept the research projects carefully sequestered; there's now a lot of empty space inside the ship again.
Timo Saloniemi