This seems to be an intentional choice, apparently due to the computational load of running such formatters? (thread on all MathJax supported SEs)
On second thoughts, I'm not that sure if the BioAc SE will ever need as much math notation after all - even though it would be nice oc. Some of the solutions to overcome the lack of math notation are in this QA thread: LaTeX on Stack Overflow?
Change of mind EDIT:
On 'third thought' enabling math formatting would actually be awesome. As pointed out by some of you, even simple formulas are a pain to read without notation, and it seems like I'd overlooked the frequency with which we use them!!