Yeah, it's been one of the known issues since some of the old mods that used Immortality. Without some kind of big problems to go with it like huge opinion maluses Immortality is kinda dull unless you got it as a really weak ruler, and even then the little bonuses that add up usually make you a good ruler before too long.

Vampire mods got around it by making everyone hate vampires, but even then it wasn't a real problem once you got any sort of real power.