Luongmyno
I'm not the creator of this flarum extension, but let me tell how I feel about the situation.
First of all, It would take a lot of effort to make a web-based WYSIWYG formula editor. Given that the target audience is quite small, it doesn't worth trying. Of course, Microsoft could afford this expenses to conquer the market, but no open-source project can.
Fortunately, LaTeX formula markup is powerful and already familiar to lots of people, especially who came from academia where it's kind of de facto standard; there're good libraries for rendering this markup as a part of webpage. So, there is almost no reason to prefer MathType-like approach, except noob-friendliness. But noobs are not going to typeset complex formulas anyway.
