Caves, bridges, shooting galleries, and more.
The reason why we should have rope bridges is not just for tree houses but for above ground level access to various areas of our base/s. You could have a central building tower, and watch towers surrounding your building, each watch tower would have access by rope bridge rather than ground level access or building component walkways. It would keep you off the ground especially if you have a Land Mine Field etc down below surrounding your Base. You would also avoid any land based PvP or PvE attacks, unless of course someone tries shooting up at you but that wouldn't be a problem if you upgrade to Armored Rope Bridge. You could also use Rope Bridges inside your building this would save you a lot on building structures, and possibly introduce a new interior building style. Why build floors when you can build a bridge?He even worked his idea out in Photoshop.