Do you want your family mourning your death and fighting over who gets your stuff at the same time?
Someone will feel entitled, someone will feel frustrated, someone will feel overwhelmed, someone will contest, someone will argue that’s not what mom would have wanted or that’s not what dad would have wanted. Now your estate is paying legal fees to sort out the fight instead of going to your loved ones for which it was intended. Now your life or death medical care is on hold while the court sorts out who makes the decision, or if the court itself will make the decision.
Someone will feel they know best, but who knows better what you want than you? We would rather help you plan today than referee your loved ones tomorrow.