And to address your last sentence, I think it’s important to understand that for a skilled engineer it _does not necessarily_ take more time to write better code!
Every profession has conventions on how their solutions are expressed. Go against the convention, and you'll make us work harder to understand you. This is not appreciated.
If you want to establish a new convention, show us how yours is better.
Similarly the field is called computer science. Not every convention an engineer follows is simply because "we have yet to find a better one". I can certainly agree that the landscape has and will continue to change over time, but there are some truths when it comes to designing systems.
As for gleaning understanding, tests are useful for learning "what" a system is meant to do, but wholly meaningless when we need to know "how". Often the latter becomes the important bit when we need to extend/modify code.
I agree that there is a balance to be had. Not every LoC or module needs to be perfect. It's often more important (and practical) to choose a suitable level of abstraction, and make sure that the code at that level has an amount of agreed upon standardization.
Now I can agree that having decent documentation or even literate programming [1][2] contribute in large to understanding but it's never a replacement for clean and maintainable code. It's the same as architecture where if you're sloppy with the designing a bridge it can (and often will) come crashing down resulting in high expenses and lives lost over something that could have been prevented had others been able to understand the design and question the practices. The same applies to code.
[1]: https://cs61.seas.harvard.edu/site/pdf/p384-bentley.pdf [2]: https://jhidding.github.io/adhesion-code/