The colour isn't needed, you're right. But that doesn't mean colour coding every now-and-again doesn't hurt either. It makes learning which to some beginners dull, seem quite colourful and interesting. It's literally one of the key things that we tend to notice colour more than black.
Life's not a waste of time and time's not a waste of life so let's stop wasting time, get wasted and have the time of our lives - Mr Worldwide 3:18