I should probably re-word myself:
Sky Battles were decent. The one Sky Battle I did in XY, I really liked it! My biggest concern is that... Sky Battles, much like every other niche battle format Game Freak introduces with the exception of maybe Triples, doesn't really get much exposure in-game. It's like... why bother creating the format if you're not going to do much with it, y'know? You meet probably one or two Trainers that you battle via Sky Battle and that's it.
I'd much rather people grow more accustomed to Sky Battles via important battles like Gym Leaders, Elite Four etc. Imagine having one of those battle be held in the sky; that would really shake up the monotony of Pokemon battles in a good way!