Determining a dogs true diet is challenging because our dogs have been bred to be kept pets and we are feeding them meat that isn't alive, it's been sitting around and/or frozen. So sometimes a high quality plant based diet could be healthier in the end. They aren't running around in the wild hunting down their prey, they are receiving their food in a bowl with no effort but some begging. And they aren't getting nearly the amount of activity they would in the wild. Canines in the wild work hard for their food.
The amount of time that dogs have been intentionally bred is a mere BLIP on the history of canids.
And dogs have only been fed commercial food for the last 50-100 years--prior to that (for a few hundred years back at most), most domestic dogs ate a combination of table scraps, raw meat, and killed prey. It takes MILLENIA to evolve and adapt to a different diet, and canids have not (fortunately!) been fed commercial food anywhere near that long.
More on this: http://rawfed.com/myths/cooked.html
As for activity level: Um, well, sure. But that just means that they should be fed LESS than a wolf eats, not that they need to be fed differently. Carbs make dogs fat--which is why we have all these fat, diabetic cats and dogs out there now--but meat doesn't do that to carnivores unless it's fed in huge quantities. My 60 pound dogs get 2 pounds a day and maintain trim figures and glowing good health on that.