Originally Posted by
polyphonica
This question was actually addressed in a recent interview, and they basically said the issue is that instances aren't saved, and since people will generally want to be able to do all the things a normal house can do anyway (both now and into the future, like airship building, etc.), it's better to just let everyone have full/real houses rather than creating a less-featured one. Of course, on busy servers, they'll need to add a ton of capacity to do that.
In terms of the "cheaper" issue... I think they simply don't have a vision for housing being something that's for everyone, but rather they want people to see it as an investment they work towards in end-game (and a bit of a gold sink). The reverse auction would help with pricing if there were enough supply (which there now is on some worlds, but not others).