This is what it looks like on Math.SE:
This is what it looks like in the SE hot topics list:
Sometimes you want to display raw LaTeX code rather than preview it, for example any question about LaTeX might include LaTeX code that should be shown as is. That is the reason why http://tex.stackexchange.com and http://stackoverflow.com lacks MathJax. Note that a question about LaTeX question is hard to programmatically distinguish from a math question because LaTeX questions might also contain math expressed in LaTeX.
I am not sure whether it is even worth fixing. If a title includes a LaTeX code it is probably quite easy to read even if you know little LaTeX, as in the example you provide, so you will not gain much in fixing it (and complex LaTeX expressions won't fit in question titles). Also, as pointed out MathJax requires massive resources to run and it would probably mean that the inbox gets slower which would be against its purpose of efficiently informing of new things.