What I meant is that I think it implies the general playerbase on the xbox (backed up to some extent by the marketing) is likely to be young and male. Which may have some bearing on the choice of sex used.
Regarding sales: My sale does not count as I bought it in 2014, and ME1/2 through steam, ME3 through origin. Digital sales (especially through Steam) are generally never calculated in these charts, which are usually retail only.
I do not think you can safely say that the most copies were sold on the xbox, certainly not by now. Think how many additional copies of ME1/2 were bought in a single steam sale (which is how I bought them).
What I really think (as Bioware will have access to, especially through origin - although even then I often play in offline mode) is that Bioware have realised that a sizeable proportion of the playerbase on certain platforms does play as female characters (whether they are actually female or not is open to question - certainly on this forum there are a high number of female posters) and have therefore realised there is a market there. I think this shows in the improvement of the female inquisitor compared to femshep.
Of course, based on a few posts above this direction is likely to make a few people weep (only manly tears of course, whilst looking stoicly into the distance and not betraying any other hint of wussy, girly emotion) but I for one welcome this as a positive change.