One of the downsides is that when you show your code to other developers who don't have the necessary visual bandwidth, they get uncomfortable.
One of the few things syntax highlighting actually helps with is for catching typos in keywords. (To the trained eye, this could be replaced with just bolding or italicizing the keywords.)
Today I'm using "the colorful words" again (as non-technical associates have described syntax highlighted code), and still looking for a syntax highlighting theme which does not look like crap. (Gruvbox is the closest I've gotten yet.)
Giving each identifier its own color (e.g. https://medium.com/@evnbr/coding-in-color-3a6db2743a1e) is another interesting idea.
- Comments and string literals can look like code without being code, so they get their own separate colours to make it easier to quickly scan past to where they end.
- Types live in a different dimension from the rest of the code, and tell me a lot about what it does, so they get a different colour.
And, finally, the one I've been trying for a while but am still not convinced about:
- Structural keywords (for loops, branches, etc.) get a separate colour as well.
All these colours are of course relatively neutral. I'm especially confused by people who use bright red for anything. That's a colour I use extremely sparsely for actual errors and bugs.
That was five years ago. It felt weird for about ten seconds. These days I find code with syntax highlighting very noisy and almost impossible to deep read.
It's quite possible that it was always like this, but that I was numbed to the effects and lacked reference points.
Whatever the case, I don't miss it at all.