How come no one has yet investigated whether or not Ha'ro's suggestion can be proven or disproven from first principles?

As far as I know it has been disproven from first principles. If we should put an equal probability on all non-mangled worlds, then we should expect to find ourselves in a high-entropy world, unless I've misunderstood and the number of non-mangled worlds stays exactly constant under entropy increase.

I think it would be possible to prove that if you made a monkey type out a random program with the universe as input, it would output your mind with a probability proportional to the squared amplitude of your world. I think if you studied the orthodox Deutsch/Wallace/Greaves decision-theoretical account of probabilities in MWI, you would understand how to do this proof, even though they don't put it in these terms. But I'm not sure.

*cheerleads for orthodoxy*