TOS was extremely expensive, even if it looked cheap by the late-80s due to advancements in effects and production technologies.
In 1987 dough, it'd be $666,172.84 per episode. Each TNG episode had cost at least $1million per episode, after divvying up the whole season into individual episodes' needs and all the other budgeting fun stuff. So TNG got nearly double that of TOS and as season 1 of TOS had 29 episodes.
$190k to 2024 dough is $1,850,113.27...
And how the money put into "The Cage" could only be recovered if other shows used the same sets, etc, hence the clever ways of putting "The Cage" into "The Menagerie", airing WNMHGB despite it being a pilot (hence being aired nearly mid-season and with big changes that would have confused many on initial viewing) and so on.
Heck, a lot of 60s shows had sets for hotels, airports, etc, that clearly looked like a small studio space cutoff. This started to change in the 70s, of course, as location filming became cheaper to do. Side fun note, NBC's other show, "I Spy" (1965), helped pioneer a lot of efficiencies in location production - which was crucial as they flew around the world, but still had time for the occasional studio shoot where it's... still sometimes obvious that it's a studio set, but that's par for the course and a fair amount of it matched up considerably well for the time.