That is a lot of mesas, very nice.
I understand the cropping seems unlegit, but having vast amounts of land that is completely uninteresting that nobody has settled in if a new update comes out that could generate much more interesting things, I think that is a waste of space. We need to crop some of the old land out. If people actually colonize land all the way from Matolony to the mesas, I'm fine with preserving that whole region, but otherwise a huge chunk of land will just make the world file (which has increased by more than 500 MB since it was cropped) much bigger than necessary. That will slow down mapping, downloading backups, uploading it, and so on. It makes it much more heavy to deal with.
Imagine that the black spots between our explored areas wouldn't be explored and the terrain gen got updated. You would have lots of tiny areas with chunky borders everywhere, and considering people prefer walking 8km in one direction and going back through another path instead of exploring neighboring areas closer to home, a new terrain gen would make the terrain fit horribly together in a lot of places. Saying "never crop again" is simply an 100% impractical rule. Instead we should discuss which areas deserve to be preserved when we crop, but we already do that. If most people want to run across 2 km of land to go to the mesas, we could just preserve that area, no reason to preserve the entire world for that.