I believe one problem with math.stackexchange is the lack of discipline by newer users when it comes to using MathJax. Let me elaborate.
Much too often, one can see a question posted by a user that is completely unreadable. The user simply writes his equations inline and waits for some magical fairy to come and make the question "look nice". In my view, too many resources are being spent on editing formulas in MathJax instead of actually answering the questions.
I know what the counterargument is: there are a lot of new users in math.stackexchange, users that the community wants to accept and help them grow. Many of them will eventually become useful to the site and we do not wish to scare them away by punishing them for not using MathJax. Therefore, I believe the problem would be some sort of three (or $n$) strike rule.
The rule is as follows: the first time a user publishes an "ugly" question, the question is flagged as "not using MathJax" and the user is politely but firmly directed to the MathJax help page. He is also told that in order to ask questions on this site, he is expected to know how to use MathJax. Then, if the user continues to use ugly formatting, he gets warned every time this is done, up to some number of strikes, where he is either banned or just starts to lose reputation.