Of note, I have not seen any caves/dungeons really yet. Lots of castles/towers, etc.
But yet to see someone claim DOWN 2 or 3 claims.
I'm going to try to make a mini dungeon, but the problem I see immediately, and why you probably don't see too many is that the claims have height, but not width. So you can make tower dungeons I guess, but making a sprawling dungeon just isn't possible because you're so limited on land. You'll just end up with 2/3 rooms, stairs up/down, 2/3 rooms, stairs up down etc. I wish you could turn the claim box on it's side to have more width in building. It may be more possible now that you can have the 3rd attached claim, because you can now make a large square claim.
Another thing I see issues with, is the grapple. It kills any kind of platforming, or open level design. There's also no falling damage, so pits are not scary. And theres no keys or triggers to guide a certain path.
Finally, I wish there was an ability to have a 'loot chest' where a person can only take 1 item per day or something. Because I thought of putting a chest at the end of my dungeon, but someone will just take everything and ruin it for everyone else.
And of course there are no npcs. So really, it's hard to make a dungeon when you don't have any of the tools to actually make a dungeon outside of geometry.
But despite all that, I'm going to try to come up with something!