The problem with terrain tool manipulation

Is anyone else annoyed by the fact that we can't build walls right next to a hill? There's always a 1x1 distance between high terrain and the actual building. 

Quick example of what I'm talking about:

I know TwistedMexi's Terrain Pack exists, and that I can sort of cover up this issue by placing rocks and bushes or whatever but let's be honest just reworking the terrain tool to actually cover the walls would be such a game changer...

(another possibility I could live with would be to make the foundation an actual accessible floor (after reaching a certain height, so we can place doors/windows/walls there and make like a basement above the ground or something) since terrain actually doesn't leave a gap there, but that seems even more unrealistic to implement than the option above lmao)