1) I frequently play for 12~ hours a day 4 times a week (my job only requires me to work 3-12's each week) and thusly I am at the FC house frequently so perhaps not 24 hours a day but certainly a large portion, I have never seen this player online, nor at the summoning bell/marketboard near their home in the 4+ months this player has owned it.
2) It is not an FC house
3) Purchasing a house for the purpose of cheaper teleports doesn't even make sense, houses cost millions of gil, in order to pay off that investment you would need to teleport about 3.5k-4.4k (assuming 999g rate decreased to 150g) times to pay it off. That would be an insane amount of teleports to the 1 city or the 1 surrounding zone that is accessible directly from the housing district. This doesn't account for favoring a teleport to reduce its cost lower than the 999g it maxes out at, which would only increase the number of teleports needed.
4) I'm not saying it needs to be a specific use case, I'm saying the specific housing exclusive systems; public decoration, cross breed gardening, RP, chocobo leveling, etc., should be utilized.
5) SE has already made it abundantly clear over the 7 years this game has been out that they will only slowly add housing due to system/server limitation, expanding housing is not something they do frequently. This makes housing ownership a luxury that should be maintained. IMO, this is completely fine, but if the bar is set so low (zone in once every 45 days) demolition should never be turned off. And in the long run what it would do; at least in the way I see it, is that it would foster a closer knit community among the people who play frequently, who own houses and utilize their features, if someone owns a house and is never there and never online except for zoning into their house once every 45 days, that is only hurting the people who want to desperately own houses and partake, and making more headache for SE themselves.