With technology moving on as it does, patenting single genes for use in targeted tests will soon become pointless. In a few years (it is happening already), exome sequencing, followed by variant confirmation via Sanger sequencing (directly sequencing the gene, not using a patented kit) will be the normal way to do diagnostics. Nobody will be paying for a single (or even multi) gene testing kit.
Now, if companies decide to try and patent entire exomes (or genomes), things may turn nasty.
My 2 cents (or pennies, where I hail from).
As to your final point, I would tend to disagree. Who decides what is 'good' for the human race?
Idiotic thing to say for an X-linked disease such as DMD. Females can carry one copy of the gene without showing any symptoms, therefore natural selection cannot breed this disorder out of the population. Males with the disorder generally die before they are old enough to father a child.