Several different entities support color changing; trains, train stops, cars, players, and more. I think that support for this should be extended to common factory machines.
This would be serve a few purposes:
- Better organization. Which furnaces are those? Oh, I set them to blue, so those are smelting iron.
- Sight reading. Color-coding would make it faster and easier to read what a factory is doing at a glance, especially if the colors are visible in map view to some degree.
- Aesthetics. Speaks for itself, really.
- Mod and scenario functionality. Lua-controllable building tints would have a variety of uses. For instance, a mod could recolor buildings to show new information, or a PvP scenario could color-code each team more thoroughly than is currently possible.
- Accessibility. People who have difficulty perceiving certain colors could recolor parts of their factory with shades that they can easily distinguish.
Finally, I suggest a addendum to this: Swatches. Inspired/stolen from another factory game, a swatch is a global color palette. You can assign a building a swatch, and then edit the swatch to edit the color of every building that uses it. This is conceptually similar to how train stops will soon copy the color of another stop at the same time as the name. If you use colors widely, swatches would reduce the effort of recoloring parts of the factory.