[Susiron]

A lot of the reason people do lock things is based on them not wanting other people to enter locations they are currently and actively using. If the world is no longer in actual use, many of the locked areas will no longer matter to the users who locked them-- especially farms and areas that would be easily susceptible to annoying grief or people using them without paying.

The world's large enough that the odds of someone finding a well-hidden build somewhere are probably slim anyway. Even if they did, unless the user left signs with their name, the build would remain completely anonymous.

I don't doubt there are players who don't want people to look at their builds, but I also don't think it's as big of an issue as you're making it out to be. I imagine there are other users who would also love to see the world in spectator mode, not just myself. It would make it easier to explore the world and replicate underground builds and locations