Here's a link that discusses protein in dog foods....
The Dog Food Project - Is too much protein harmful?
I personally feed my dogs a 36% protein dry food and have had no problems with it. My dogs weigh from 3 to 12 pounds and range in age from 1 to 7 years. Their activity level varies...from a little lazy to very active. None are fat.
I look at the AAFCO guidelines as similar to RDA requirements for humans. They are both minimal levels to maintain health. They don't speak to the levels needed to provide optimum health, which often are much higher.