Throughout my years of playing Wurm I have found two mechanics which I thought were counter to the idea of a sandbox world. The worst offender was the immutability of clay, tar, and peat tiles. This issues was finally addressed and I am beyond grateful to the devs. The second issue is dealing with rock surfaces below water and at high slope. I would like to see the following changes made and options added.
1) Allow concrete to raise rock up regardless of depth of water. If it seems to easy with the current concrete system then perhaps it would be better to add concrete forms or an enhanced form of concrete like the "heavy concrete" suggested in the post below.
2) Add a way to use concrete on high slopes. For this I would suggest a new item, Concrete Form. It would be built on a tile boarder and allow the user to 'Raise Corner' beyond the current limit. This came to mind as I have done several months of surface mining and a few times I went one slope too far but there is no way to repair the mistake. One would think that in a sandbox any terraforming should be reversible, at least on the PVE servers.
3) In consideration of my assertion all terraforming should be reversible on PVE servers I would like to suggest a tool which, like a dredge do for dirt, allow players to lower underwater rock below the current limit.
As with all tools it is possible for each of these items to be 'abused' but, that one might do evil is no reason to stop another from doing good.