I think a few colors more are planned anyway, but I think, at least two or three gray-tones should be available for the font 
For example for the description Id suggest sth between 60 and 90% gray, the one available is to light from my perspective.
It would be best if they could allow for custom colours using HEX codes.
Custom colours please! Seeing the drama that recently stirred in the notion community due to the change in colours, having personalised colour palettes would be quite well received.
Not exactly related, but AFAIK, custom CSS support will be implemented sometime in the future so it should be possible to have customized palette. However, it would be even greater to have a color picker through a plugin
Yep especially for things like tags, so that a certain tag is always the same colour in your personal anytype system.
You seem to know a lot of things 
It’s so disappointing that this forum is neglected and mostly used to spot bugs.
There’s been a few similar suggestions of a custom CSS now. I’ve been suggesting a way to proceed here: Add options to change font size and style - #34 by UBr
WHAT DO YOU RECOMMEND?
Instead of having a choice of ten colours be able to select any tag colour you wanted.
HOW COULD IT BE DONE?
When you click the three dots, the current ten options are shown and then an optional more colours and the hex selector tool pops up.
REAL WORLD USE CASES
Two cases spring to mind. I am a blogger with three blogs they all have the same logo in three different colours. I would like to have all the tasks and notes for each blog in it’s own colour.
I am also a genealogist. On Ancestry I have a colour for each of my Great Grandparent’s surnames. I would like to use the correct colour for notes and tasks relating to that family line - and more beyond.
RECOMMENDED ALTERNATIVES
I can’t think of any work around to this.
ADDITIONAL CONTEXT
This sort of links to Colours-code for Projects, Tags, Sets, Collections