Contrary to popular beliefs, your family isn't automatically given the right to make legal decisions for you when you lose mental capacity.
In Singapore, without an LPA, your family has to go through the process of applying for deputyship (ie, getting court's approval to appoint a person to make decisions for you when you have lost mental capacity). The usual application process is a longer process and can take 3 months or more, and is also more expensive. This excruciating process could take a toll on your family when they cannot access your bank accounts to pay for bills or make decisions for you.
Don’t confuse an LPA with a will. A will can only be processed after a person dies.
Read more: Lasting Power of Attorney (Singapore)