No, the game does operate on cubes already. Noise is a cube, with noise traveling an equal distance vertically as it does horizontally. Crossbow range is a cube - 20 tiles omnidirectional range, including vertical. Travel distance is a cube - one tile up is equal to one tile horizontal. Everything in the game treats distances in all directions as equivalent.
Does a dwarf take up a full 27 cubic meter volume? No, but neither does a cat take up a full 1 cubic meter volume, nor could a dwarf fit in one, much less a dragon. That's just an unreality of the way the game treats all creatures as occupying the "upright" portion of a tile, while infinite numbers of creatures can crawl. Arguing on the basis of what creatures fit is therefore meaningless, because elephants and dragons and giant sperm whales all have to crawl to share space with a rabbit.
Further, one of the major reasons 3 meters is used is because vertical distance is the easiest thing to assume. 3 meters/10 feet is the height of a story of a house. Each z-level in the game is equal to a full story of a building, and each z-level can house a different floor.
If you were to put it in terms like Minecraft or Terraria, which have clearly designated areas for their tiles, Minecraft has 1 meter per tile, but needs 2 tiles height for a humanoid, and a floor tile, which adds up to at least 3 meters per floor. Terraria has 2 foot tiles, and requires 6 feet vertical and 4 feet horizontal clearnace, plus 2 feet of flooring, meaning 8 feet/2.5 meters vertical space per floor minimum, although an extra tile to fit some furniture is common in housing. Furniture in that game is often quite large, as well, with beds also being 8 feet long/2.5 meters in length. Fitting one of those beds into a single DF tile would require a horizontal tile length of at least 2.5 meters, if not 3.
Yes, these are dwarves, not humans, but they're also digging in stone, and having some slightly thicker masonry in the ceiling/floor for support also makes sense for them.
So, you could argue something closer to 2.5 meters, but that winds up making calculations really messy. 15.625 cubic meters instead of a clean 27, for example.
By the way, although Toady has never confirmed anything, when pressed to think about housing size, he gave 2 meters as his initial guess as to room size, and given the things that must fit inside a tile, 2 meters is definitely the floor, not the ceiling.
http://www.bay12forums.com/smf/index.php?topic=60554.msg1511922;topicseen#msg1511922I think they are fine given what I've read (that the floor space for a cottage for a family would be between, say, 25 and 125 square meters, depending on affluence and local customs and whatever else). Throwing out 2m arbitrarily as a tile edge, we'd be at 100m^2 for the floor space and 1536 m between villages, which I'm more or less comfortable with (I read an aerial survey for medieval sites in England which put average nearest village distance at 0.89mi or something, and we talked about how this might be varied earlier). Since we are on a grid, even with a single room the outer walls take up 24 tiles and the interior is 25, even though the outer walls shouldn't take up a lot of space. If they are divided into a living and storage area, which might involve an internal partition, then the floor area would be cut down an additional 5 tiles, putting us down to 80m^2. I don't know how different the cottage shapes are going to be, but within their plot there will end up being variations in terms of overall size, gardens, other structures, furniture, items, etc.