LuvTaycieGirl - GREAT post
While I do think it's important to feed a high quality diet, it's equally as important to find what works for each individual dog as well.
When it comes to protein, it's not so much about the simple number in the percentage as protein, as it WHERE the protein is coming from. You will see some foods that have hardly any meat in there, but their protein is 28%-32%, meaning most of their protein is probably coming from PLANT sources. Which is not good. There's a lot of "grain free" foods out there filled with potatoes.
IMO, there is no set protein percentage that a dog has to have... it all depends on the individual dog and what works for them. There could be two foods, both with 28% protein, but the dog could do horribly on one and not the other. It's more about the ingredients agreeing with them.
I think Wellness is a good food, but it doesn't work for Jackson. He got terrible eye boogers on it, and his coat became more dull and less shiny, and he produced more poop. Therefore, I don't like Wellness for him but it doesn't mean it won't work fine for other dogs.
I do know that the original studies that convinced people that high protein was bad for the kidneys was done on RATS who are omnivores... and all the protein came from plant sources... so IMO, it makes the argument completely invalid.
Find what works for your dog.
I would never feed a 'grocery brand' like Kibbles n Bits, etc, and I probably wouldn't ever feed anything by Science Diet, nor would I recommend it. But I would not be opposed to feeding a food simply because it's lower protein, or even has grains in it.