[danielatc]

Interestingly there is something like syntax highlighting in natural language too. One example is that all nouns in German are capitalised which helps a lot in the context of ambiguity. To give you an idea of a case in which it actually might help:

  The complex houses married and single soldiers and their families.

vs.

  The Complex houses married and single Soldiers and their Families.

Other languages use different markers to indicate different parts of speech.

A point that could be made is that (written) language evolved for a long time and the concept of "syntax highlighting" is embedded in at least some of them. Probably because it has proven useful.