Basically, humans don’t develop color words for natural colors. As they invent artificial colors, they invent words to describe them. Before there was blue paint or dye, the sea was described as the color of dark wine and the sky was white. Helen of Troy’s eyes were grey.

Apparently, Klingon kids grow up with two crayons, a dark pencil and a white page.

While your history of the invention of the color-word blue is essentially correct, it does not apply to every language. There are languages that exist which do not have dedicated words for certain colors, and yet the native speakers of those languages can make use of those colors just fine.

English, for instance, has eleven basic color terms, but that doesn't stop Crayola from producing a box of 120 different crayon colors. We create compound terms to describe various shades of a basic color. When your language has fewer basic color terms, you don't see fewer colors; you just classify them differently. You can recognize all the same shades of colors; you just need to use more compound terms to zero in on them. And speakers of languages with fewer color terms have one advantage: when they don't need to be exact, they don't have to be. Klingon poets, for instance, can see the sun in the sky and describe a jul SuD in a chal SuD, a parallel no English-speaking poet could make. They recognize that it's a SuDbogh jul 'ej wovbogh in a chal SuDqu' (the skies of Kronos are usually depicted as green — and the fact that I have to clarify this demonstrates my point perfectly), but they don't need to say all that. They're both SuD.

And since there are so few color words to choose from, why bother with a generic word for “color”? Just ask it like the joke: “Doq’a’?”

(A) Because Okrand told us how they do it: chay' nguv? (B) Because sometimes you do care about shades, and Doq'a' doesn't allow you to drill down that far. (C) Because receiving a wink and a joke answer to a serious question is irritating.

You don’t have to ask {SuD’a’}. If it’s not {Doq}, it must be {SuD}, right? And if it’s neither, then it isn’t really a color. It’s just dark or light or it looks like something in nature for which there is no color word.

qIj and SuD are color words too. Shades of black and white are colors. Those four words apparently cover the entire range of the Klingon visual spectrum, and anything in nature will fall into one of those.

This might be why the joke is considered funny to Klingons. Klingon armor, weapons, and blood are not red, so how could a warrior be red? It’s such a silly idea. Mwahahahahahahahahah...

The joke is not asking if warriors are red, but if warriors are Doq. Klingon blood is Doq, as are "nearly all Klingon bodily fluids" (KGT).

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SuStel
http://trimboli.name