Assume for a moment that all TeX literature, TeX software, TeX files etc. got destroyed in some global cataclysm. All information about TeX survives only in the mind of a few TeX gurus, or something like that.
So we would be "free" to write a typesetting system from scratch, without any need for backward-compatibility holding us back, but using our knowledge about historical imperfections of (La)TeX, if any.
What might be the main differences between the current (La)TeX and the new typesetting system?
Edit: I'm not asking "what will all the differences be" or "what controversial opinions might circulate". Rather I'm asking "what differences are likely to be a consensus". If a historical site gets destroyed, there might be debate in which style to rebuild it, but there will be consensus that fire safety should correspond to modern strict standards, rather than historical standards.
I'm asking this because I'm wondering about certain aspects of the history of (La)TeX (hence the
tex-history tag), specifically how imperfections were kept for historical reasons (e.g. need for backward-compatibility). Otherwise it's difficult to understand why certain aspects of (La)TeX exist but are deprecated or discouraged from being used; why (La)TeX is the way it is (complicated in some cases); how wrong the opinion is that a simpler-to-use but equally powerful typesetting system would be possible.