I'll add a few cents here as I just knocked this off my bucket list and went to visit the crucible (before they moved the tournament)
Expansion is difficult with the building location. Moreover, unless you're in the first couple of rows, you already need binoculars! Thankfully World Seniors wasn't sold out, so front row seats were easily available for a few quid.
2nd point is hotels. No where near enough accommodation to handle any expansion. Yes they could grow with the event, but if they only fill up once a year, doesn't make much business sense. The crucible will need to attract other events to fill up 5000 seats year round.
3rd point from Houssein Vafaei. I guess he didn't recognize the smell, but pot is legal now in the UK, and the odor of wacky tobacky penetrates the whole city, which besides a few blocks around the city center, is very much run down. Dings club is only a few blocks from the crucible and in a pretty sketchy area (not Glasgow sketchy) but pretty bad that I wouldn't want to go there at night.
Lastly, at least for seniors where tickets are only 20, the media production for 5 live (and action 5) is enormous. Ticket sales won't even cover the salaries of the camera operators, let alone all the other people involved. The ad revenue from the broadcast must balance that out, but somehow I doubt it. My prediction is this was the last world seniors in the crucible! I also don't think that the demand is particularly elastic. Getting to see Jimmy White play in the crucible from the front row for 20 with may be 300 in the audience. (Or Ken, or Drago) Sure Ronnie will fill seats and Judd and the rest of the class of 92. But anybody else? Better to have a full house, than a half empty stadium for most matches...