For all "it's fine as it is" people: Try fighting all your battles manually, and not savescumming.
For me, even with some save scumming, I still burned through at least 10 companions, and half of Vlandia and Sturgia (the two factions that most fought) in about ten years. Whole clans went extinct.
If death was used in auto resolve as well, I am pretty sure at least half of Calradia would be gone after a decade.
The combination of the AI constantly declaring war, lords constantly escaping from imprisonment and respawning with another army, and the AI's tendency to pointlessly suicide even noble units makes a 10% death rate way, way too high. I can't wait until they lower it drastically. I guess until then I will mostly autoresolve and savescum.
EDIT: Look at it this way. In every battle, one side loses, which means on average, a lord will go down at least once every 2 battles (but probably a lot more). With a 10% chance to die each time they do that, the life expectancy of a lord would be at most 20 battles. How long do you think it takes a lord to fight 20 battles?