* Less works for developers who no longer need to pick, integrate, and maintain a third party library for rendering.
* Faster user experience, as the MathML code can be served directly and rendered by the browser (as opposed to parsed and rendered with the javascript engine).
* More options. Maybe LaTeX is not the right choice of syntax (more people write math then professional mathematicians and PhD students). As translating to LaTeX is hard, translating to MathML is easier (I know, I’ve written one my self).