Main reason? SE pursued a housing path that places heavy limitations on the supply and type available. There is a valid argument that FC houses are central hubs for socializing and should be given a slightly higher priority. On the other hand, FC rooms are by no means an adequate substitute for personal housing. Additionally, many FC houses serve fewer than 4 players, at least in my ward. All of these are symptoms that in-game housing availability in its current form is suboptimal.

SE did a great job of creating a housing system that is fun to decorate. However, there is sadly a huge availability issue that I've seen no plans to address effectively, ever.