Your next of kin is not automatically entitled to run your affairs or make decisions for you, if you are unable to do so.  No one has any right to deal with your assets or make medical decisions unless you have given them prior authority.  Therefore if you lose capacity to deal with your own affairs without an LPA in place, someone would have to apply to the Court of Protection for a Deputyship Order, which can be time consuming when you need to make quick decisions in a difficult situation.