The irony of the whole situation is that Celestia decided to go with a painting for her official portrait because a photo would have meant the camera adding ten pounds.
@Princess Trixie vi Equestria
I guess there’s no especific rule about “what to feature” (despite that obviously it should be a safe image). From my knowledge, the staff proposes art, does an election and the picture with the major quantity of votes win, without taking into account details as if it’s already popular or not; the point (I guess) is to offer a nice picture for all the users during the three days that the image is being featured.
But I’m not part of the staff, so I’m just guessing.
@Princess Trixie vi Equestria
Featured image isn’t only about showing under-noticed images/artists. It’s really just about showing great artwork we like.
The only thing we try to avoid is featuring the same artist over and over again.
Why this got featured though? this was famous from start. There’re still a lot of awesome art little know about, myself saw a Cadence draw from 2 years ago only with 100 upvotes that deserved four digits.