I actually thought the admins of the page read the stories and featured the ones they liked! Well, surprise! It's just a system that chooses stories to feature based on the views, likes, and faves they get, not on how good they actually are!
The conclusion was that writing some popular nonsense is the best way to get featured, regardless of quality. That ain't my style. My aim isn't really to get popular, but to use the whole phenomenon of pony fan fiction to develop my literary skills. If I get a group of followers, even a small one, that genuinely enjoys my work for its quality and respects me as a good writer, then my dream will be fulfilled.
I'm on the right track, then.
Now that my mind is no longer clogged by worry over that blasted Featured Box, I can write in peace. Thanks, AbsoluteAnonymous.