Who should have a Power of Attorney?

The easy answer is that everyone should have a Power of Attorney, especially for health care.  A Power of Attorney can be a lifesaver, but a lot of the time, by the time the Power of Attorney is needed, it is too late to get one. For example, once someone becomes incompetent, it is too late for them to give a Power of Attorney.  Likewise, if there is an accident and you need someone to make health decisions, you may not conscious to give a Power of Attorney. 

So, yes, it is vital for everyone to have a Power of Attorney. However, it is important to only pick someone you can trust.