To put it concisely, gameplay would be immensely improved if a few changes were made to vassal mechanics:
This would be so much more fun and satisfying than trying to paint the world one color, and I think aiming to establish a global empire of vassal states is at least a little more palatable than aiming to conquer the world.
- Add a parallel option to Annex Vassal which will instead make the normal slot-taking vassal a free vassal, much like the Holy Roman Emperor gets. It would be identical in every way except for ending with making the vassal a free vassal. This functionality already exists, called privileged vassals, and the time to integrate them and opinion malus to other vassals could be identical.
- Count privileged vassals as the overlord's borders for the purpose of CB and claim fabrication (good enough, easy) or allow the overlord to fabricate and declare on behalf of the vassal (better, more complicated).
- Make vassals gain an increasing chance of rebelling on monarch death as their opinion of the overlord decreases. This puts a dynamic limitation on how quickly vassals can be established, since monarchies can't leverage the legitimacy reset on monarch death.
This would be so much more fun and satisfying than trying to paint the world one color, and I think aiming to establish a global empire of vassal states is at least a little more palatable than aiming to conquer the world.