If there is no such feature, then either lords can't die, or their deaths are politically meaningless, like in VC. Oh, and of course the game gets easier and easier because you're some immortal OP lord who just gets eternally better, until you get bored and restart, erasing your legacy. And for what? So events can be made up in your head? I get that this needs to be done to some extent, but is it not better when the world operates plausibly? And more dynamically? Otherwise, why not write a book?
Maybe they should add in an immortal trait for those who want to keep on going, but we all need this feature, because without it, the whole game is shallow and repetitive. Death is part of life, and history is made up of many lives taking up the legacy of others. Making the game worse by allowing such a system to be disabled seems like a waste of time, because even its opponents will come to love it.
Playing as an heir is not the same as starting a new game anyway, because you could inherit equipment, titles, relations, and even have a better education. The difference is that you now have a parent to avenge or other claimants seeking your titles.