You need to ensure that your bitcoin can be successfully transferred after you die while also ensuring that it can't be unintentionally transferred while you're alive. Let's say your give your bitcoin wallet password to a trusted friend/lawyer to hold onto in case you die. Now you've just doubled your attack surface for adversaries to steal your bitcoin. At the same time, you can't only keep your bitcoin password in your head or your bitcoin will become worthless once you die.
People are already not good about estate planning today, I wonder how many millions of bitcoin will be lost in the next couple of years as bitcoin millionaires die without making sure there's proper paths towards retrieving their assets.
However, with cryptocurrency, the gap between how securely a single person vs. a dedicated entity such as a bank can store money decreases significantly.