if someone else finds your lost BTC they can't just pick it up and use it, or if you die it can't easily be passed on.
What do you mean they can not pick it up? Finding your lost bitcoin means finding the private key of the wallet and in that case they become the owner of the bitcoin.
I always keep my secret keys available to few people. Not the whole key phrase but the portions. My next of kin will be asked to find them and solve the puzzle.