I just feel that choosing at will to pulverize all stone instantly makes something that already borders on being far too easy even easier.
I mean, you are fucking chewing through solid stone, easily all the way to the earth's mantle. How little logistics do you want that to take? There is absolutely no need to make this any easier. Zero, nil, nadda.
To argue this in a different route:
Currently, the game utterly ignores most aspects of the Conservation of Matter and Energy (which is one of my personal pet peeves, and part of why I started the Volume and Mass thread), and in some ways the game can really be altered by this decision:
Currently, you pretty much vaporize stone. Legendary miners can dig nigh-instantly through solid rock, and produce a single stone leftover for their work.
Consider, on the other hand, how anthills are dug. Every piece of dirt that an ant digs away must then be transported out the other end of the anthill. The entire reason it's an ant
hill is because those ants dump that dirt in the first open space they find - right outside their front door.
We're talking about a major change in the way that players must consider their fortress-design - building above-ground as a way to get rid of stone becomes fairly attractive when you're actually FORCED to get rid of stone, rather than simply let it litter all your hallways when you mass-designate whole mountains to be plowed into oblivion because darnit, there might be some more coal in there! (Not that Mountain-Top Removal doesn't exist in real life, but dwarves don't have to live with any of the consequences of those actions...)
I've been in a lot of arguments about difficulty and complexity lately, (Although, frankly, this one isn't complex at all - rock takes up space is pretty darn simple.) but I've been arguing for this difficulty in making things because the game fundamentally is based upon having dwarves who can manufacture useful products out of raw materials... and these raw materials are, for the most part, infinite in number, and as such, inconsequential to the player.
I do think that more player actions should have positive or negative consequences tied to them so that one has to actually stop and consider what they do, rather than mass-designate or assume that stone or food or glass or whatever are infinite.