Interesting concept. One thing they could do as a start would be to allow alts to share a house with their main in addition to perhaps coming up with something like this. Elective demolition should at least carry the same benefits as auto demolition when it comes to recovering gil for the house itself.
Those of us who own multiple homes bought them because our alts can't even teleport directly to our own house let alone use it when they get there. This obviously was before 4.2 given buying multiple privates is not an option anymore. I have an alt on Mateus who bought an apartment in the same ward as another alt so she could at least avoid having to tele to the main city aether and so on. The apartment at least offers direct teleport to the ward and the apartment aether quick access to the house location. The frustrating thing though is once you get there the house is essentially useless can't do a thing with it. Even more frustrating is I can share that house with friends who have full access whereas my alt can't even use the mender.
It's why some of us will create a FC so that they can in fact share a house. I have 4 level 90 alts on Balmung who share a FC in Brimming Heart along with a few select friends. I have no interest in a personal there given that FC serves my needs.
Personally given the increase in the player populations I was surprised not to see housing restricted to one per account or even perhaps one per DC now that we can DC travel. On the other hand if that were to be a thing the ability to share even on other servers and DC's should be part of what someone should be able to do with any alt regardless of server given after all the house does belong to the account just like the alts belong to the account.