My first house was literally due to it being the default. I never thought about it. My ward was dead so no one ever asked.
My second house was a medium, and one day someone said liked my yard and asked was I going to let people see the rest when I finished. I was like ‘people do that?” Then I opened it up.
The mansion I just got in the last patch I had locked because it wasn’t decorated. I only have the top two floors done right now, but I ran around yesterday greeting all of the new residents I saw and giving out housewarming gifts, so I unlocked it so they could come see it.
Also, the message you get when you try to do it doesn’t help.