What is a "real space station"?
Terok Nor was stated to be an ore refinery, and much of its volume no doubt is dedicated to this, even though we never learn the full specifics. It would appear the pylons served a major function there, not only in conveying ore and extracted minerals from A to B, but also as areas of processing - when DS9 is upgunned by Starfleet, room for major new weapons is found at the pylon roots, even though Starfleet apparently wants to preserve the other industrial function of the space station, that of a cargo transfer hub.
Terok Nor also served as the headquarters and top-level accommodation of the Cardassian occupation force, and was well armed to perform an orbital intimidation mission even if this was never discussed. It would be the habitat function that Starfleet would have the easiest time restoring, as thrashing that would have been low in the list of Cardassian priorities. Starfleet would also hurry the re-establishing of the command functions, even though those would be the ones the most severely scuttled. Anything having to do with weaponry would be secondary; anything relating to cargo processing tertiary at best (they didn't even know there would be much traffic originally, until the wormhole was found). So those vast unused cargo holds would not count as readily useful resources for expansion, not during the first season yet.
Indeed, the episode that best expands on the former functions of the station, "Civil Defense", would see our heroes start ripping out ore processing systems and confronting booby traps in the third season only...
Timo Saloniemi