The answer I have heard the most (with a source citing the official confirmation) is that green, brown and gray bricks were omitted from the LEGO palette because the company wanted to discourage kids from building tanks, planes and other realisitc military hardware.
Early LEGO colors were inspired by the work of Mondriaan, which mainly consists of white, black, red, blue and yellow. These primary colors were considered to be most appealing to kids.
From the book “Brick by Brick”:
The new product was patented in 1958 and within a few years bright
yellow, red and blue Lego bricks, colours inspired by the paintings ...
A practical engineering concern could be a reason to limit the colours used for molding in ABS plastic.
The colourant added to the base plastic can affect the physical properties of the molded part. Depending on how tight the dimensional tolerances are for the finished part a separate mold may be required for each colour.
Perhaps the Lego group process ...
I have a background in precision injection moulding, although not to the extremely tight tolerances of Lego. Here's why a manufacturer would try to reduce the number of colours they used, particularly in the old days.
Most resin (the raw material) nowadays comes pre-coloured, especially for a large customer like Lego. That wasn't the case fifty or sixty ...
The color of the 2x4 plate and 1x2 jumpers in the photo appears to be regular Dark Blue:
The greenish tint you mention is likely discoloration. Here is an example of a discolored regular blue piece (right) next to a fairly new regular blue piece (left) for comparison:
How uniform or consistent the discoloraton is depends on the cause and/or ...
There has been a slight change to the Pearl Gold/Warm Gold color recently that might explain the difference in color between those pieces. See this article on Reddit. Perhaps the right two “Flat Dark Gold” pieces are the newer recolor of Pearl Gold? I recall Jang from JangBricks talking about this as well in his videos.
Here is the picture from the Reddit ...
Version (Program): 4.3.11.
Version (Brick): 2670.
We're using Extended Mode (Black Backsplash) of LDD, so we can have full access to all colors. I have not tested the other two modes, Default (Blue Backsplash) or Mindstorms (White Backsplash).
If the model is in Default Mode. No problem.
Copy the build to ...
This is an excellent question. Here's my best guess as to why this is.
As you've pointed out, LEGO System Minifigures were made with yellow heads from the start for a specific reason. On Lego.com it states:
We chose yellow to avoid assigning a specific ethnicity in sets that don't include any specific characters. With this neutral color, fans can assign ...
Manufacturing logistics play a part in this decision. If you have to maintain six different dyes or pellet hopper combinations in the injection molding pipeline in your factory, that is a different story in terms of cost than maintaining sixteen or thirty hopper combinations or dye vats. If the pellets are pre-dyed (as I believe was the case), sourcing these ...
Most bricks in sets are picked from large bins of a given colour/shape when making up a set, and used in many different sets. Hence there is a cost advantage to limiting the number of colours and hence the number of different brick.
I have no idea where to find any sources for an answer, but I can offer a guess.
When it came out 70620 Ninjago City was the set with the most different elements ever made (That wasn't hard to verify, if I can remember how, I'll check later if it still is, and if any other contenders offer more colours), a guess is that they will come in many different ...
The fact that so many sellers have it and named the color consistently pretty much rules out discoloration.
As to why the item isn't on BrickLink (or Brickset), I can only see the following explanation:
it's in a set which hasn't been inventoried yet (but your seller would probably have known which one)
it's been produced for something else which hasn't ...
This article potentially provides some insight to the type of research that product developers, such as Lego, might use to "better" their products. It's title is obviously meant to be humorous.
If research suggests that babies/children react to things like skin tone, it ...