The CGA palettes were designed with three main objectives: good contrast on composite and black and white displays, high contrast productivity UX, and simple ttl circuitry. There was a limit of 16 colours, but if you wanted to step up resolution you had to compromise by selecting fewer colors. A major compromise choice was resolution vs colours. High resolution cost you your magenta and yellow. Have a google for the mode 4 and mode 5 pallets and mathematically why they are the way they are, it’s super interesting if you’re in to retro tech.

In the later era, as EGA and VGA gained, I think CGA became a bolt on by some game devs, to accommodate that dwindling audience, so the problem was compounded by it being very second class citizen.