Thousands of nukes wired to extremely old computers. Landmines buried throughout the world. Governments everywhere building military robots.
Sooner or later the whole world is going to find out all the things about legacy systems that programmers already know.
How can we warn them? How can we prevent them from doing what it's obvious they're going to do?
The next time somebody tries to get you into some argument about Programming Language X vs. Programming Language Y, skip the whole question and spend some time on this one instead. It's a harder question, and answering it will make a bigger difference to a larger number of people.