Personally I find it superfluous and annoying - you see the title being constructed (4 'jumps'!) in the browser when you visit any page displaying that title.
But in running texts (on other SE sites as well) chemical formulas are often written this way, because if offers the possibility of subscripts.
Should we edit and remove this kind of formatting in titles?
Here is a meta.SE question about backticks in the title where the answer states Markdown isn't run on the title whatsoever. Any special characters get converted to their entities. This suggests that any formatting should be avoided.