Said it before and I’ll say it again:
Two-color decks only exist today because of the economics of producing decks ***hundreds of years ago.***
Even when it became possible to mass-produce cards, it was still very laborious and expensive to use multiple inks.
Being attached to a standard that old is silly, especially when the standard was arbitrary or forced by the limits of totally outmoded technology.
It makes about as much sense as getting offended that the other players at the table aren’t wearing giant powdered wigs.
Or that there isn’t a wax seal, a tax stamp and string protecting each fresh deck.
The only reason to prefer two-color is habit. And it’s an easy habit to break, worth doing because four-colors have a clear usability advantage.
We have digital print technology now that allows for as many colors or design innovations as one likes. We should use it.