Hmm, I can see the change to clay will quite significantly change how I play around my base.
It used to be that I'd choose a flat site for my base, and a flat site for my garden, and a wide flat area for visibility and safer melee play.
But for digging clay I'd deliberately go some distance from my base so that the cavity I create didn't mess with my bases flat area and create a potential trap for myself.
Now all that has changed. I can build on any 'soil', regardless of its topography, and simply work on leveling the land as I go.
So my digging of clay/soil now will simultaneously give me cleared flat land for gardening, and flat land for melee, clay for the forge, clay for cobblestone, and for players who use trenches, they can also gain those defenses at the same time, while in the past all these 'tasks' were seperate time consuming activities, all with different pre-planned objectives.
It'll save me time. I can get a lot more done all around my base with this degree of 'multitasking' with the ground. In fact, I can imagine I'll be stripping my base area of all its soils, right down to stone over time, all the time gaining materials, and ultimately making it harder for digging Z's to reach me once the base foundations hit stone.