Tier color-coding

[sankarshan]

Right now, the tier-color scheme in Factorio is all over the place: belts go yellow->red->blue, electric circuits go green->red->blue,
assemblers go gray->blue->yellow, inserters go gray->yellow->blue->green (furnaces are 3 completely different-looking entities, while electric furnace is also bigger - if you insist on keeping the electric furnace bigger, at least make the 2 tiers of the regular furnace similar-looking).
And there is no second/third tier for refineries, chem. plants, miners, centrifuges, pumpjacks, etc. Why?

I propose making a unified color scheme for tiers
(and if you feel really fancy, you can make the higher tier entities more beautiful than the more-hack-job-looking lower tier entities),
and adding a second and third tier (or may be even a fourth/fifth?) to as many of the entities of the factory as reasonable (what with the power pole wood->yellow->grey color scheme?). So that as the factory improves, its' overall color will change, thus making the improvement more noticeable, and allowing to estimate progress (and upgrade potential) at a glance.

The hallmark of a top tier game is when the players spend as little time as possible identifying what they see, since each entity is distinct enough to be easily identifiable at a quick glance, while managing to convey all the relevant information during that same quick glance, assuming the players are experienced enough to know what to look for.

[Illiander42]

This is intentional on the dev's part, so that factories are always colourful and messy.

[Yodo]

Huh, makes sense that it is intentional. Different colors can also help to find things more quickly in the factory (assuming the player has played enough Factorio, and tends to use a consistent tier of buildings).

Also, as to thing X (refinery, train...) not having a higher tier, I like to think that modules and better fuels fulfill the same role, and with the DLC you also have quality.