If General Motors started manufacturing vehicles that every once in a while exploded for no good reason, the public would demand it to be removed from production and either fixed or scrapped altogether. Whereas there will always be instances of innocent people going to jail, when it's a matter of life and death, I don't think we can support a system which so obviously favors the O.J. Simpsons of the world over you or me.
Since we can't realistically devise a system that provides equal representation to every single criminal, I feel that we should err on the side of the handful of innocents that are going to have their lives cut short in the name of "justice". Even if it means a thousand other bona fide murderers will spend the rest of their lives in jail cell instead of on a gurney, I think the lives of a few innocent people are worth it.
The very DNA testing that this guy helped bring to the forefront DRASTICALLY reduced the possibility of innocent men being convicted of crimes of the type that end up with the death penalty.
He is trying to implement a solution to a problem that was already drastically reduced in risk factor, by many magnitudes.