No wide open fields or jungles to explore, barely any well-designed caves. Its just that final fantasy shit again.
You can't even travel to the different islands via lapras, thiis has to be the first pokemon game where every major location is entirely locked apart aside from fast travel

There are no interesting towns or cities, Poni island is just a fucking wasteland

Say what you will about Hoenn, Sinnoh, and Unova, but in a straight trek through the main quest you miss a hell of a lot more than you do in Alola