Visually, Friendship is Magic is a terrific cartoon, and I love the design, but there's not a whole lot to do in the way of fanart. Much of the main cast is just entirely based upon their coat color, and how their mane is styled and colored, such as Rainbow Dash's blue and rainbow, or Pinkie Pie's curly mane and pink. You can do some more stylized stuff, but for the most part it'll still be the same build with some artistic differences, such as stronger shading and higher detail on hair.
Humans, however, are extremely different, which is why fanart is such a draw. Rainbow Dash, for example, can be a pale-skinned punk rocker, a cheerful-if-pushy, thin teenager, a colored buzz-cut teen, as a giddy teenager in a blue jumpsuit, or even posing as Rosie the Riveter.
But it's not because I like taking away that it's about ponies (an inherently 'girly' thing), or trying to find some kind of roundabout way to be 'attracted' to these characters, it's because I like Rainbow Dash. Rainbow Dash could be a Goddamn frog for all I care. I love her for her character - the brash, sometimes insensitive, ferocious, wonderful ball of awesome she is. Humanized Dash is just another way for me to celebrate one of my favorite characters with all sorts of different artistic directions.
The fact that there's really hot, hot Dash/Rarity action is just a wonderful bonus.