Hi (looks like I've already starred your repo at some point months/years ago)!
The motivation was not to replace art with technology, but to preserve/resurrect an art that was going away, by truly capturing the human understanding[^1]. When the rest of the industry was perfectly content with the deterioration of typesetting, Knuth set out to capture the aesthetics of the best journals of the past. A quote from the Mathematical Typography paper I linked above (https://websites.umich.edu/~millerpd//docs/501_Winter13/Knut...):
> At this point I regretfully stopped submitting papers to the American Mathematical Society, since the finished product was just too painful for me to look at. Similar fluctuations of typographical quality have appeared recently in all technical fields, especially in physics where the situation has gotten even worse.
Frankly, I think the "replace art by technology" impression is a very shallow one, that I alluded to earlier. When Knuth wrote his “The Concept of a Meta-Font” in a journal (Visible Language) mostly read by designers/typographers, many of them wrote letters in response (https://shreevatsa.net/tex/metafont/concept#reactions). What you can see is that the best of them were supportive (even bringing up new points like how it could be useful in educating the next generation of font designers), but some were sharply critical, more or less resenting this intrusion of technology into their art medium. But now a few decades later, basically all fonts are distributed and stored digitally anyway, except that (without METAFONT) the shapes of letters are now basically just stored as binary blobs / sequences of numbers, without any METAFONT-like understanding of typographically relevant quantities like (say) x-height, comma depth, slab thickness, etc. Which one is truer to the art?
(Not a rhetorical question BTW: as in the Bigelow/Southall quote above, one could say that Knuth's approach is to achieve typographical/artistic excellence through understanding, but the artistic approach is visual and intuitive without a cognitive component. But this is a different complaint from the "replace art by technology" take.)
(BTW apart from the default Computer Modern fonts designed by Knuth, who based them on earlier Monotype fonts, almost all fonts used by people with TeX too are designed by font designers, not computer scientists.)
[1]: Related quote from Knuth (sorry paraphrasing from memory): “People say that the best way to understand something is to teach it. I say no: the best way to understand something is to teach it to a computer.” But then again he has also said: "Science is what we understand well enough to explain to a computer. Art is everything else we do."
The motivation was not to replace art with technology, but to preserve/resurrect an art that was going away, by truly capturing the human understanding[^1]. When the rest of the industry was perfectly content with the deterioration of typesetting, Knuth set out to capture the aesthetics of the best journals of the past. A quote from the Mathematical Typography paper I linked above (https://websites.umich.edu/~millerpd//docs/501_Winter13/Knut...):
> At this point I regretfully stopped submitting papers to the American Mathematical Society, since the finished product was just too painful for me to look at. Similar fluctuations of typographical quality have appeared recently in all technical fields, especially in physics where the situation has gotten even worse.
Frankly, I think the "replace art by technology" impression is a very shallow one, that I alluded to earlier. When Knuth wrote his “The Concept of a Meta-Font” in a journal (Visible Language) mostly read by designers/typographers, many of them wrote letters in response (https://shreevatsa.net/tex/metafont/concept#reactions). What you can see is that the best of them were supportive (even bringing up new points like how it could be useful in educating the next generation of font designers), but some were sharply critical, more or less resenting this intrusion of technology into their art medium. But now a few decades later, basically all fonts are distributed and stored digitally anyway, except that (without METAFONT) the shapes of letters are now basically just stored as binary blobs / sequences of numbers, without any METAFONT-like understanding of typographically relevant quantities like (say) x-height, comma depth, slab thickness, etc. Which one is truer to the art?
(Not a rhetorical question BTW: as in the Bigelow/Southall quote above, one could say that Knuth's approach is to achieve typographical/artistic excellence through understanding, but the artistic approach is visual and intuitive without a cognitive component. But this is a different complaint from the "replace art by technology" take.)
(BTW apart from the default Computer Modern fonts designed by Knuth, who based them on earlier Monotype fonts, almost all fonts used by people with TeX too are designed by font designers, not computer scientists.)
[1]: Related quote from Knuth (sorry paraphrasing from memory): “People say that the best way to understand something is to teach it. I say no: the best way to understand something is to teach it to a computer.” But then again he has also said: "Science is what we understand well enough to explain to a computer. Art is everything else we do."