You can, indeed, do a lot without colors. I actually find it a lot less distracting to have various shades of the same color and highlight with bold, italics, and a couple shades of gray. The other day I was wondering if I could add some non-ascii chars to htop's monochrome mode (looked like a pain, will pick it up later) to explore textures instead of colors.

I remember using Think Pascal on the Apple II (too slow to be of any use) but it did a great job of highlighting the structure of the program under the source code. This is what I want syntax/semantic highlighting to do for me.

These screens are higher resolution and can have multiple shades of gray, which is much more than what those pioneers had to communicate with their users.

Horrendously expensive though.