TeX is about representation, not semantics, by design. To do anything useful with a function (like plotting) you need to get semantics.
An often cited example: what is f(x+y) ? Is it function f with x+y as its argument, or constant f multiplied by (x+y) ? TeX gives you no clue.
Or what is this i in your equation? Is it an index variable, or a square root from minus one?
You as a human figure this out by looking at the context and using domain knowledge. So does a "TeX to HTML/MathML converter". It is ultimately built on heuristics, and cannot be otherwise.
That's why I said basically "for the same reason a paper page is not interactive". It was designed this way!
The goal of TeX was to generate beautiful printed page. The need for semantic structure was not anticipated. To do semantics you need a "semantic version of MathML", or a language used by Wolfram's product, etc.
An often cited example: what is f(x+y) ? Is it function f with x+y as its argument, or constant f multiplied by (x+y) ? TeX gives you no clue.
Or what is this i in your equation? Is it an index variable, or a square root from minus one?
You as a human figure this out by looking at the context and using domain knowledge. So does a "TeX to HTML/MathML converter". It is ultimately built on heuristics, and cannot be otherwise.
That's why I said basically "for the same reason a paper page is not interactive". It was designed this way!
The goal of TeX was to generate beautiful printed page. The need for semantic structure was not anticipated. To do semantics you need a "semantic version of MathML", or a language used by Wolfram's product, etc.