It’s actually a very valid reason - that one initial block shape you proposed would mean a ton of new assets to get it to fit. You’d need either 2 separate wall pieces that are both shorter than the walls available now or a singular 90-degree corner piece with irregular sides. Then you would need to make one for every tier of building material. Add it all together it quickly balloons in the amount of meshes, icons, and the memory footprint it takes up in things like the crafting menu. It’s a small addition but all the stuff that goes into that one small thing quickly adds up to a lot of hours of work and all the cost associated with that.