One of my biggest complaints with X and Y was that it didn’t contain enough content after finishing the main game. After defeating the Elite Four in X and Y I expected there to be a new area or two that I could travel to. Sadly, this never happened.
I still vividly remember only booting up my copy of Pokémon Y 2-3 times after beating the Elite Four. While there were a few things to do after the game’s completion, such as catching the legendary Zygarde, the game as a whole was probably the most lacking entry in the series as far as postgame content goes. Hopefully, Sun and Moon will entice the player to continue adventuring around the region of Alola after completing the main story.