I can see your point, David, and I mostly agree! 
On the computer, I've used a MM program to outline nonfiction (text books, assignments, etc), but I used a program that - like Scrivener - became "invisible" as you used it, most notably didn't insist on my using the mouse. So on the computer, I really just use it like an outlining program, as I find it very useful to be able to see more on one page instead of having to scroll down heaps. But since discovering Scriverner a few years back, I haven't updated my MM software and can't justify the expense either.
However, I am a big fan of MM on paper for a quick "minddump", or a deep thinking session about a complex issue. With a pencil. And no, I never use different colours in a first draft of a MM - I find switching pens too interruptive. If I my issue is so complex that I want to revise and make a second or third or fourth MM of the same subject, I may add colour. But again, on paper. Big, large sheets of paper.
