Very, very few of us are unable to build flat surfaces and soil construct hasn't really taken off in the game. We need to be able to build large structures with ease and the best way to aid players will be to introduce a mold system. As a researchable item molds could transform this game to the levels of Minecraft creativity. Imagine being able to select a square flat surface which could be rotated in all axis and when confirming the location gets filled with soil from your canisters. Also you could introduce concrete or steel in the constructions depending how high and heavy the structure is.
Also concrete could be used to stop boulders and plants appearing on player flattened surfaces. (Roadmap has water, so with clay and sand.. Maybe!)
You can them open this to Steam Workshop so players can share and download creations direct into their game (Depending if all the materials and research the player has achieved/collected).
The soil manipulation is the main feature of the game, so why doesn't it appear in the Roadmap for further development?