Introducing an easy to read & easy to typeset notation which doesn't work well by hand means you're creating a figure, an illustration to be looked at like a photo, not something to be worked with.
The blackboard-bold fonts are an interesting example of this, with computer typefaces being created for what mathematicians use in the real world. (Though Knuth and Serre and some other mathematicians don't approve of them in typesetting.) Besides, typesetting is a small part of the usage of notation; most of it is written in private by mathematicians for themselves or collaborators, in the classroom for students, in talks for each other, etc. (Typeset papers are a low-bandwidth communication medium, though good for broadcast and archival.) While it may make sense to optimize the ease of creation of typeset mathematics (and that is what Knuth etc. have done to some extent), changing the notation (for this reason) is not a sensible place to do that.
(Some related links: https://micromath.wordpress.com/2010/09/24/psychophysiology-... http://sites.math.rutgers.edu/~zeilberg/Opinion60.html http://okasaki.blogspot.com/2008/01/why-i-dont-use-powerpoin... http://sites.math.rutgers.edu/~zeilberg/Opinion78.html Section 3 of https://arxiv.org/abs/math/9404236)
Maybe if math notation were forced to be easily typesettable, it would be simpler or more programming-language-like.
[1] https://mitpress.mit.edu/sites/default/files/titles/content/...
Note that some of these notational improvements may actually make it harder to typeset. For example, the second part of Knuth's paper "Two Notes on Notation" (https://arxiv.org/abs/math/9205211) introduced improved notation for the Stirling numbers "of the first kind" and "second kind", replacing easier-to-typeset but less informative notation like S(n,k). This notation has gained a good degree of acceptance, the paper won a writing award (https://www.maa.org/programs/maa-awards/writing-awards/paul-...), and another paper citing it calls this “The best thing that has happened to the Stirling numbers during their 400 years of chequered history” (https://www.jstor.org/stable/2974533?seq=1). (See also a talk of his on Notation https://www.youtube.com/watch?v=KjbuyB4dQa0&list=PLoROMvodv4... for which someone has taken notes: https://crypto.stanford.edu/pbc/notes/misc/notation.html)
I think there are valid questions to be raised on which people to optimize for: whether the students encountering the notation for the first time, or the people who use it every day for years. In either case (to make my point again) it's a question about people, and not about the technology — a programming-like notation isn't better unless that's how the people who use it think (or want to think).