I really like the idea, and most revertable covers are super cool in design. Because it's so inconsistent I never do it. Most covers don't feature all the details that are on the outside of the box and I like to have everything "the same", except for Special or Limited Editions, if that makes any sense? Even if covers feature all the same details on the inside I wont do it. afraid to damage the cover or bend it wrong and make it more fragile. I really like to keep my collection as clean as possible. Still, having art on the inside of the box is also really cool.
Never, because as nice as the illustrations may be, it feels weird to me when they don't have the usual age ratings, writings and whatever is normally on a game box. I would much prefer if they simply replaced the pictures and kept everything else as is.
I usually don't do it because a lot of times they don't have the PS4 logo on the spine for the flipped side, so it drives me crazy having a game on the shelf with the others that looks out of place. Wolfenstein 2 for example does this on the reverse of the box art so I just kept the original box art side.