The medieval times which are quite closely corresponding to the DF timeline, were not pleasant at all. People could die of illness, killed by a random ruffian, killed when their carriage fell of a cliff, children could drown in a gutter, spoiled food was quite common in taverns and serious poisoning could be uncurable. I can see no reason why even a whole family couldn't be poisoned by a jealous servant, other noble, die in a tragic fire or fall off a said cliff together. That is, unless of course, you want to carefully track the number of poisoners, arsonists and dangerous cliffs.
In any case, I can see that you are not a fan of my idea. Fair enough and may I say, perfectly understandable. You like realism and consistency. I respect that. But at the same time, note that this will not ruin your game. Nobody will force you to use that option. And if others would like to use it, would it bother you that much? I think that the game should customizable in many ways and this is one of them. If you want to start as a historical figure so that you will not break the hardcore realism of the world - that's fine, but if you want to meddle a bit so that you can play as the character you want - that's fine too in my book.
No need to argue about anything, really, if you can play your way and others can play it their way. Not only in this case but in any other. That's healthy.