In my personal opinion, believe it should stick with targeting the female audience. Why? Because the show empowers young girls so well! It shows little girls that you can be smart like Twilight, be strong like R.D. and A.J., be soft, sweet and shy like Fluttershy, outgoing party-animal like Pinkie, or even a priss like Rarity and still be an amazing, lovable woman! Now, am I saying this means the brony fandom should stop watching the show? No, of course not! The show is family based really, but it just more specifically reaches a younger female audience. That's why I love this show! It shows girls come in all shapes and sizes and it shows that they know what's best and that they can stand up for themselves!
Overall, I think everyone can watch it, but the show should stick with the young female audience thing they're doing. If you have an issue with how "girly" the show is-- a show which is meant to target a female audience anyway??-- then just don't watch it, simple as that. If you have an issue with little girls having a show for themselves, you're the issue, not them.