I always wondered why no one is doing syntax (or, semantical) coloring/highlighting for stuff like mathematics or sheet music. It could even help with simple plain text.
The reason is probably that "it's always been like that", just like keyboard layouts. Though one could argue that coloring would be not be very disruptive and backwards-compatible, so it wouldn't hurt traditional reading much.
I've always found it interesting how video games (e.g. Legend of Zelda) will make certain key words in text a different color. It works well—but why do we only do it in video games?
The reason is probably that "it's always been like that", just like keyboard layouts. Though one could argue that coloring would be not be very disruptive and backwards-compatible, so it wouldn't hurt traditional reading much.