Well, on the flipside you actually would never know that a noble hero died unless he got buried...if you're an adventurer.
If you are an adventurer, that's something akin to the media not caring enough about you. A noble's death is broadcast so everyone in the realm knows. An adventurer's death is not so much. Have you ever noticed that whenever a famous politician cheats on his wife just about everyone in the world who has a TV knows? Contrast it with an average working person who cheats on his wife, and they just go to divorce court and not many people know or care.
Sure, the family and friends care but in BM, we have no mechanic to tell who's a friend. We do have a mechanic for who's family, and the family would certainly know the adventurer die, if the player chooses so. The entire family is played by the same player, after all.
Now why should it be mechanics? Well, right now our "friendship" system is by roleplay. By the same token, finding out about deaths of adventurers is by roleplay, in that...well, yeah, you have to find out yourself that he's dead. No messages announcing it. For nobles, it's just because that's one of their perks or something.