In practice, most of the industry has been writing ridiculously inefficient code for decades, and I wish more people would pay attention to that 20%, or the 3% that Knuth described.
Or better yet, I wish some groups don't irreversible sacrifice performance with frameworks and architectures that are impossible to optimize, no matter how the code is written.
I agree with both of you - there's no reason why software should be as inefficient as it is, and there's also no reason why code should be as unreadable as it is, and those goals aren't mutually exclusive.
Except that it is, and it tends to be development speed.
For example, real world React apps tend to suffer a lot from performance issues, specially when compared with vanilla html+javascript or even the old but true server-side rendered HTML, but it also makes it trivial to implement and rewrite complex UIs that UX designers love to put together. Would it make sense to argue for performance options which lead to productivity hits?
Always.