Usage of the male pronoun is historic just like the usage of the plural pronoun. The choice to go agains hundreds of years of usage is very political.
Personally I prefer the plural when you do not know or do not wish to highlight the gender. It jibes more with my personal sense of right.
I end up feeling suspicious of an author that uses she about ~75% of the time since it seems they remember to use it more often when referring to people in a customer/student/etc role or with an example question/mistake, yet more often use he or avoid pronouns when referring to an expert or people with titles.
Meanwhile, they works perfectly fine, if it confuses someone that is their problem and if I said her problem there it would be because I was sexist for one reason and his for another. :)