I've just found this paper, which seems to address some of the issues I want:
25 Years of TeX and Metafont: Looking back and looking forward — TUG 2003 keynote address by Nelson Beebe [TUGboat 25:1, 2004]
TeX has lasted longer than many other computer software technologies.
This article reviews some of the history of TeX and METAFONT, how they
have come to be used in practice, and what their impact has been on
document markup, the Internet, and publishing.
TeX has several design deficiencies that limit its use and its
audience. We look at what TeX did right, and with 25 years of
hindsight, what it did wrong.
We close with some observations about the challenges ahead for
electronic representation of documents.
Are there any other published references?