I believe that among all the engineering tenets, #9 is the most important, relevant and (in my opinion) impactful. I say this because the code in anything defines how digital technology works, and digital technology is by far the biggest, most influential, life-impacting and ever-present form of technology, innovation and invention since the start of mankind.
Its very important to maintain a balance between human and machine interaction. If one confuses the other the balance will be broken. This tenet is saying how engineers should not write code purely for function but for the response and perception by people that interact with it. They should delve into psychological and social realms as the tenet says, and should work to create the most immersive digital experience possible without ruining the harmony with the physical world. There are a few large corporations that seek to create a seamless communication between the two, “perfecting” the experience, such as Apple (during the years Steve Jobs was in charge). The company has always aimed to create a simple-to use (to minimize frustration) yet powerful operating system experience on all of the devices they own, from mobile devices like the iPhone to desktops and laptops. Not only do they strive to minimize the friction between person and machine interaction, they have developed a tight and invisible connection between all of their own machines, creating a machine-to-machine environment that creates an even better experience as you switch from one to the other without problem.