I learned about progressive enhancement as a way to take a simple html site and add styles and scripting to enhance its appearance and functionality, as needed, without interfering with the basic purpose of the site. This keeps it simple, fast, and compatible. If bandwidth and browser supports a feature, it will display it, but these enhancements should never interfere with the basic purpose of the site.
This has opened my eyes to other systems that could benefit from this perspective on purpose while integrating new designs and techniques.
A while back we had a truck that would be over 20 years old now. While towing a trailer down the freeway, it suddenly lurched and sputtered, losing power while sounding terrible. It still drove and we were not far from our destination. We took the next exit for the slower backroads. The shop found it suffered from an emissions warning and put the engine in limp-home mode. Perfectly functional, just reduced power to allow you to drive to a shop. I’m fine if you want to add emissions monitoring to a vehicle, but it should never get in the way of its purpose, especially since this can be dangerous or worrying. Why can’t a car’s basic function be separate from all enhancements?
Imagine an old military Jeep which the US Army was trained to fully disassemble and reassemble in just minutes. It is a simple and reliable machine with a specific purpose. You can paint it and add modern wheels without affecting its main purpose. You can add any electronic device and modernize the interior. You can even make dramatic style changes to give it a newer appearance. All this to give you a modern vehicle without affecting the true purpose. If one of those electronic additions fails, it should not cause the engine to go into limp-home mode or strand you somewhere by shutting off or refusing to start.
We can apply this to any system. Start with its most basic purpose, doing one thing well. My rule is that any enhancement should not affect this most basic purpose but either be cosmetic or add a feature that the main purpose never relies on and is never affected by.