I think its varies person to person. I look at the AKC registration as additional assurance that my puppy came from quality bloodlines. I would also hope, that by ensuring the breeders are registered that my dogs are examples of improving/maintaining the qualities of the breed. I love Yorkies because of all the qualities/standards the AKC is trying to uphold. I have nothing against mixed breeds, but I wanted pure Yorkie....
As you said, some breeders are still registered and are not breeding to the standard. However, I personally look for breeders who are. I know the AKC does inspect breeders. I would think breeders would take it upon themselves to live up to the AKC standard.
There are always exceptions to the rule.