Also worth mentioning is the fact that while the addition of 'per-map-cell' (and/or per-tile-cell) colouring methods + the abilty to directly paint colour to the map/tiles might be intuitive enough for the text modes (just 1 matrix colour), it almost certainly would not be for the bitmap modes (2 / 3 matrix colours).
So on balance, I would have to conclude that offering 'per-cell' matrix colouring as a project data export option (only) would be the right choice.