Why I'm mostly not a fan of coloured text (in terminals or elsewhere)
I recently read someone who was unhappy that in this day and age, a Linux distribution specifically chose not to enable text colours in its default shell dotfiles (obligatory source). They have a point about the general situation, but also I disagree with them in practice.
On the one hand, the hand of theory, it is 2021. Our environments have been capable of coloured text for a long time (even if some people chose to turn it off), but here we often are, not using that capability. In many ways the default text environment is still single colour, with use of colours as the exception instead of the normality. In one sense, we really should have good use of colour in text by now.
On the other hand, the hand of practice, I'm glad that colour isn't used much because much use of colour in text is terrible (along with use of other methods of text emphasis). One technical reason for this is that many colour schemes for text assume a single specific foreground and background colour but don't (and often can't) force that, and wind up looking terrible in other environments. I run into this relatively frequently because I more or less require black text on white for readability, while many people prefer white text on black (what is often called "dark mode" these days).
A broader reason is that most colour schemes are not designed with a focus on contrast, readability, and communication (I think they're often not systematically designed at all). Instead they are all too often a combination of what looks good and matches the tastes of their creators, mingled with what has become traditional. This is colour for colour's sake, not colour for readability, information content, or clear communication.
(Even when some consideration has been put in for what the colours will communicate or emphasize, it often contains embedded value judgments, such as showing code comments in a colour that de-emphasizes them.)
There are probably text colour schemes out there that have been designed with a careful focus on contrast, readability, and HCI in general (and an awareness of the various sorts of colour blindness). But even in 2021, those colour schemes are a relative rarity. In practice, most colour schemes are various forms of fruit salad.
(This lack of careful design is not surprising. HCI-based design is hard work that requires uncommon skills, and also dedication and resources for things like user testing.)
I would probably like good colour schemes if they were common. Unfortunately, all too often my choices are either bad colour schemes or monochrome, and so I vastly prefer monochrome for the obvious reasons. In monochrome, all the text may blend together but at least I can read it.