Lawyers - and I - would like that.
Crazy's right in one regard about me. I do not like ambiguity. Take your example, suppose I am in an accident and I *do not* want my wife to have any say in my medical treatment. Nor to be held to account for any bills I incur for any treatment. Your remedy (the existing paradigm) implicitly grants power and responsibility to my spouse over and for me that I did not explicitly grant. (Yes, you can argue that I did explicitly grant those powers when I married her - but, come on, who really thought that through at the tender age at which they uttered, "I do."). My proposed solution requires me to explicitly grant her in an unambiguous manner such power.
It makes the tax laws simpler and more fair, it makes the distribution of a person's estate more clear by forcing a person to create a will, it makes unambiguous medical decisions for an incapacitated person (and let me tell you, having spent a good portion of my younger years working in a hospital, it can get awfully messy when a spouse disagrees with her children about the care of old dad). In short, things get much better defined - and more even handed as a bonus - if the law simply ignores marriage in its entirety.
