My Little Ponies Friendship is Magic, in the words of Faust in her Ms Magazine article stemed from her own RPG save the world mentality with her pony and doll collections as a child. There are willfully incorporated elements of her feminism advocacy twined within the show she created. When Hasbro limited her efforts to incorporate males as often as a functional society in her estimation would require, she wound up with a pony population that, while overwhelmingly female, lacked the sexual dimorphism to register as such to the casual viewer. Costuming and behaviorial cues took up greater meaning in the process for the viewer.
Faust wanted to portray real normal women who could accomplish great things without necessarily needing to be cookie cutter perfect. These characters worked well in teams without surrendering thier individuality. This produced some rather heroic and manly actions in an almost DND party dynamic with mature/maturing ballanced people. The Mane Six were depicted saving the world from criters you could find in a DND Monster Manual, but doing so with an emphasis on thinking and solving the problems, not just muscleing through them with superior force.
These gender equality themed roles taken on by the characters coupled with thier gender neutral pony bodies may be one of the reasons you have so many male adherants to the show. The maretriarchal society and the 6 to 1 skewed instances of mares to stalions camera time seen in the show has likely lent itself well to the other than heterosexual crowd as well. An interesting dynamic to say the least and one that goes to show that morality and heroism are not limited to traditional stereotypes.
One of the things that I noticed about the show was that for a program steeped in feminist ideals, it did not try unformly bash men in the process. You could find the occasional instance in which males were treated as capable and respectable too instead being constantly ridiculed, or chided as incompetent or stupid. That's fairly rare in the beligerant femenist realm. MLP FIM makes a point of encouraging girls to excelence and morality with out having to bash boys to do it. That coupled with gender blender roles in non sexually dimorphic pony bodies and you have a partial explanation for the marketing dynamics that inspired the advent of the brony fandom.
My two bits on the subject.