It might help the customer sort out good breeders from bad when researching, but I doubt it would change breeding practices. Good breeders are good breeders because it's important to them and they already have ethics without any organization telling them that they have to. And bad breeders are bad breeders by choice as well and they aren't suddenly going to develop ethics because some organization says that they should.
The bigger problem with such an organization is deciding what is good and what is bad and setting those parameters. Even things like health testing aren't as cut and dried as a lot of people think. We can't even agree on this board what constitutes a good vs bad breeder. I don't think it possible for any one ruling organization to be able to put together list of requirements that everyone, or even a majority, will agree on. Now add in that each breed is different and thus responsible breeding of each needs to be approached from slightly different angles, and there is just no possible way for something like this to work.
Now what *should* be possible is to get the individual breed clubs within AKC, rather than an all breed registry itself, involved in setting breeding standards for their breed and policing those breeding it.