TLDR: There is a severe housing shortage on many servers, and I think that Square Enix should fix it by giving us the option to buy island sanctuary lighthouses, regional instanced houses, customizable ships, or by adding more wards.
I am a sprout here, but when I play other games, I love playing with their housing features. I enjoy making a pretty customized house or business, then showing it to friends or opening it for public viewing. But here, it is nearly impossible to buy a house, due to the severe shortage. It took me several weeks to get even an apartment, as all of the apartment buildings on Balmung were completely full. While I do like the community housing system FFXIV currently has, it is quite vexing to be unable to buy a house or even an apartment in a timely manner. So, I have thought of some possible solutions to this problem, that would preserve the uniqueness of the current housing while giving sprouts and solo players another way to decorate.
1. Island Sanctuary Lighthouses. Island sanctuaries are already going to be instanced, so they are a perfect place to add new housing. Because they are islands, and to differentiate them from existing housing, we should be able to build lighthouses on them. These lighthouses could have a different interior layout (tall and octagonal perhaps?) than current houses, and different exterior designs than existing estates, to preserve the desirability of the current housing system. But it would still give us a cool place to decorate, hang out in, and show off to friends.
2. Instanced houses with a fixed region-based appearance. For instance, you could have a treehouse in the Shroud, a windmill in La Noscea, or an observatory in Coerthas. These would not have modifiable exteriors and would, again, be very different from current housing while still providing an alternative.
3. Add more wards to servers with high housing demand. This solution is likely the simplest, since it does not require designing any new structures.
4. Large airships, boats, or submersibles as housing. These vehicles are very cool, and would provide a way to add instanced housing that fits perfectly with lore and world design. Since these vehicles are often out at sea, or in the sky, it makes sense that they can only be visited by friends and associates of the captain. We often see them during quests, and ride them, so we should be able to buy them. We could paint them, swap out their major components, and decorate an interior with a ship-shaped layout for a change. This would also be great for players who roleplay as pirates, pilots, and fishers.
I think that any of these solutions could solve the housing crisis, or at least reduce its severity, by giving players (especially sprouts) a way to enjoy decorating a home without having to wait weeks or months for a vacant apartment or a lottery win.