The problem is not "open world" but "the ubisoft game". New region, find watchtower, reveal map, do 1 quest, attack enemy camp, liberate area, new area, find watchtower, ...
Most open worlds are also just way to big. GTA San Andreas felt huge but is tiny compared to V. And it was better for it. Modern open worlds never have a hub. A place that you actually build a relationship with and see change over the course of the game. Its always: area completed, next!