We already have TeX and anyone who writes math is used to it. Why more fragmentaton?
sum_(i=1)^n i^3=((n(n+1))/2)^2
looks to me no less complicated than
\sum_{i=1}^n i^3=((n(n+1))/2)^2
so if the goal is it quickly communicate mathematics in plain text (without rendering), I see no difference. If the advantage is that the outer parentheses are automatically resized, why not write a renderer that uses Latex and puts \left, \right everywhere? Better yet, why not go straight to TeXmacs?
I'd love to see an example of a mathematical expression where Ascii math is visibly simpler than Latex and is not just about parenthesis resizing.
((a,b),(c,d)) |-> ul x < 10 != y ~~ (dz)/(dt) !in RR -> oo
\begin{pmatrix} a & b \\ c & d \end{pmatrix} \mapsto \underline x \lt 10 \ne y \approx \frac{dz}{dt} \notin \mathbb{R} \to \infty