First time poster here :) Sharing some thoughts on the state of housing from my perspective on Zalera, which is one of the lower population servers.
We have a ton of small and a few medium houses available on Zalera and, while there are many neighborhoods that are full (e.g. lower # Shirogane wards), there are also some that are nearly completely vacant with the exception of the 3 larges in the ward (e.g. Goblet).
There's obviously a much higher demand for mansions as those tend to fill up first, but people also hang on to them to sell the plot for 1-3x the amount that they bought the plot for in the first place. I understand this practice isn't encouraged, but nobody I know is going to let their large plot auto-demo without getting substantial compensation, just due to the demand.
It would be nice if there was a way to sell your house directly or trade houses with another player (in the same way you would other items - just keep the housing permit/deed around as a physical token notating ownership) to encourage giving folks the flexibility to move into their dream plot without the risk of getting scammed, or not being able to get into the plot at all because someone is asking for unreasonable amounts of gil to displace themselves.
The current system isn't working well, but we haven't gotten much traction on asking for things to be different, and the current stance seems to be "don't buy plots from other players". Given the above, do others have feedback/thoughts we could pass along to make this a better experience for the player base overall? I'd like to hear from those on more populated servers as what works on Zalera may not work on Levi or Balmung.