No, it should be like the great cartoons of the past (aka continuing the way they are): marketing the show to little girls but have small (or large) "adult cues" so we can enjoy it with our kids (or not).
We already can make awesome fan made stuff ("don't mine at night", "button's adventures", and "Smile HD" are some that come to mind) that may/may not be geared to the younger audience. I like it when fans take things from a show, mix it up, and produce something entirely different.
Plus, I love that the voice actors acknowledge the brony fans, and I think even the writers are slipping a few bits for us ("Daring Don't" is one).