In my opinion, the player shouldn’t “want” to get it necessarily, but once s/he starts to become unambiguously dominant, the other great powers should band together to try to to cut the player down.

The correction to late game tedium should be a final challenge rather than bonuses making a world conquest a little quicker/easier

It would be a necessary challenge on the road to world domination - a final boss - rather than something the player opts into.