TLDR; Using the right dashes is about the UX of text. If you don't care about UX of the reader your points are sound.
I however--as a typographer--strongly disagree. Typograpy is both about beautiful typesetting as well as making sure that the information contained in the text is understood easily.
The former is obvious to me. It may not be to you but that doesn't make your reasoning right.
As an analogy, there are quite a few people among my friends & acquaintances who cook occasionally or rarely. They usually share the trait that they care more about eating than how something tastes. Bluntly spoken.
They commonly have one kind of oil in their kitchen (most often suflower) and they use it when the recipe demands "oil".
Usually recipes specify what oil to use. It may say olive oil or peanut oil or sesame oil. They won't have these oils and they don't care.
Even though the effect of using a different oil is profound on many levels (not even only taste). If you care, that is. Same with the dashes. Text looks and reads very different when those different dashes are used correctly.
Which leads to the information part. Why do we have these different dashes? They actually map to spoken language.
A hypen is used to pull things together. A word can be hypenated (should be read as if the hypen didn't exist) or two words can be pulled together (making the pause between them shorter) "ever-changing" is pronounced differently than "ever changing".
An en dash used between points in time or space conveys that. A distance. The spoken pause is usually longer.
And finally, an em dash, like a comma, conveys an even longer pause between the words it separates.
I must say, truth is an absolute defense, and I'm certainly one to both value calories down the gullet crude and efficiently, and to not be terribly aware of what goes on in the font fetishizing circles (no disrespect). But I do understand information coding and that obsession over a good design. For me, its been subways and metros. I've been doing redesigns, obsessive recoloring, obsessively flipping between colors and shapes and other markers in an attempt to compress all that information down to the entropy limit. So I get it. I just don't get it with typography. Its all just letters to my viewing. Once the physical squiggle has been recognized for the abstract symbol it represents, the symbol and not the squiggle is all I remember seeing. I honestly couldn't tell you the last font I ever looked at, let alone if it had serifs or [insert typography feature, no really thats the full extent I know]. I can't say I'd ever noticed (or benefited from) a distinction between dash length. Any component of a letter under a certain length scale I mentally dismiss as likely printing dirt anyway. If it works for other people, well great and mad respect for it.
So I get it. visual design language serves a purpose. An important purpose. Its not the artful navel gazing outsiders think it is. Well, maybe some people are like that, but there really is objective purpose under it all. I'd even say I agree about rules for hyphens touching their neighbors or not. For compound words it should be a train-like-in-construction whereas in a delimiter roll like range of items it should go Boston - DC.
I just can't see having a whole dedicated set of minutely different characters fit for this purpose. I dislike it for the same reason I dislike lego sets that have a particular piece in them which isn't used for anything else in any other set and never will be. It ruins the elegance of the system. It offloads a minor design problem onto somewhere it doesn't belong (namely the character set). I want to know everything while learning as little as possible. Which is why I strive for encodings that express as much as they can with as few elements as possible.
If it were me, I'd just have '.' , '-' and '_' exist at mid, bottom and top heights and be done with it. Don't like my line length? make it whatever length you want either dotted dashed or continuous. Solves every use case, extremely composable, every permutation that should logically be there, is there. .,;:' notice anything incomplete? LHTIFE notice whats missing? qbhrnujdp damn that's frustrating. KRBPF where's the rest of the set?
I however--as a typographer--strongly disagree. Typograpy is both about beautiful typesetting as well as making sure that the information contained in the text is understood easily.
The former is obvious to me. It may not be to you but that doesn't make your reasoning right.
As an analogy, there are quite a few people among my friends & acquaintances who cook occasionally or rarely. They usually share the trait that they care more about eating than how something tastes. Bluntly spoken.
They commonly have one kind of oil in their kitchen (most often suflower) and they use it when the recipe demands "oil".
Usually recipes specify what oil to use. It may say olive oil or peanut oil or sesame oil. They won't have these oils and they don't care.
Even though the effect of using a different oil is profound on many levels (not even only taste). If you care, that is. Same with the dashes. Text looks and reads very different when those different dashes are used correctly.
Which leads to the information part. Why do we have these different dashes? They actually map to spoken language.
A hypen is used to pull things together. A word can be hypenated (should be read as if the hypen didn't exist) or two words can be pulled together (making the pause between them shorter) "ever-changing" is pronounced differently than "ever changing".
An en dash used between points in time or space conveys that. A distance. The spoken pause is usually longer.
And finally, an em dash, like a comma, conveys an even longer pause between the words it separates.