How about this: Whatever the form of the material (block, rock, log, bar) used to construct the workshop, that influences (style by MAT class, hue by actual MAT) the look of the workshop surfaces and
logical workshop-specific flooring.
(e.g. whatever else you do, a butchering slab/tressle aint going to set up directly on 'carpet', in any sensible situation. Maybe allow original floor to be seen in areas not beneath/immediately around the key worksurfaces, but have an appropriate treatment where blood'n'guts could be spilt. Hey, if the artists want to get Toady to add the appropriate flag so they can draw the extra graphics, have "blood'n'gutted" overlay available for any non-virgin/not-yet-idle[1] butchers, scraps of cloth where a tailor has just worked, whisps of smoke from an active furnace, etc.)
Generic 'brick' floor makes more sense than no attempt at all to floor/pave/line the area. And I already mentioned the suspension of disbelief of forming avworkshop out of a unit building material (which in vanilla dictates the colour of
most constructions it can make, so I imagine that's going to continue at least with hint-/tint-highlighting of the however-otherwise-generic graphics. Not that I know, of course (haven't noted yet any proto-Artwork specificallt meant to depict two or more (e.g.) Masonry shops, one marble, one olivine, one nethercap, etc...) but I'm sure it's been discussed, even if it's shelved for the time-bein?).
For future expansion, at least, the more complex constructions can be mutli-partite in build. A paved road can be represented as first selected material at the (long/non-adjacent-to-prior-paved-road) edges through to the last material in the centre, or reversed, for the player to create proper roads, or else something like the Adam7 interlacing (see PNG image specification) from the queued-up materials provided, so the
clever player can draw their road-art just how they want. The bucket in the well will be hued seperately (and approoriately) to the basic block-derived element, the mechanism 'winder' and the approoriate rope/chain upon it. Dyers' dedicated bucket-tubs will reflect the actual pails provided (and maybe, inside, hints of what is - or most recently was - the dye being processed). Your Depot will clearly be formed of three materials, the perimeter features, the trading floor and whatever internal features (equiv to vanilla-layout of corner pillars, field and centre pillar?).
Those of us already OCD enough to try to colour-match everything, plus
material-match (my permanent walls are always stone blocks, of the identical stone, no cheating on this point, even if only I would know if I substituted a similar grey/white/cyan for the intended one, occasionalky) will be finally justified. Those who were never bothered need continue to be never bothered. Half-arsedely picky people will be forced to get off the fence on this issue, for once and for all.
Of course, this is a lot of potential work for the Mephday team (and Tarn, but he's not going to ask to renegotiate the contract over this issue) and I imagine it'll stay simple or at least fairly unexpanded in the initial Steam releases due to other things (but a handy project to then tie to a "Feature Drive" poll of what to update for Steam Release v1.1?).
In the meantime, I vote for generic-floor where it makes sense, transparency where it doesn't necessarily.
And/or a feature under (perhaps) the Workshop Manager section or original build-designation that allows player-choice as to full-floor, transparent-floor or the suggested centre-ground.
[1] While process-output items still remain? Additional version (for foodie locations) justifying/reinforcing the miasma cloudbby showing rotten versions of the indicative signs of use?