My pick with Latex is: Error messages look to me as complicated as C++ template errors, packages sometimes don't work well together, a lot of boilerplate is usually needed, and I feel somehow the Syntax needs too many keystrokes, like why not make {} for sub and superscript optional and everything until the next space character is sub or superscripted (and not only one character). Also writing {\rm text} feels wrong. Shdnd it be \rm {text} and maybe instead one shd be able to use $ in an equation block to get to a non italic font.

While markdown is not advanced enough, I feel the making it easier for the user to use is the right modern approach, from which maybe a full system could be designed.

Also figure placement should allow more fine-tuning (not sure how, and yes this is against the original spirit)