In a way, I'm not surprised, but in another I'm not really sure what this is supposed to change anyway. Humans have no species-specific diet, but there are a lot of things we *can* digest that aren't necessarily good for us, such as grains and starches. In no way does this mean dogs should have a diet high in starch or carbs, but it's the same as it has always been. Feed your dog according to it's own personal needs. Some dogs, some breeds, are slightly different than others when it comes to nutrition. Siberian Huskies typically do better on fish, for example. That was their diet for a couple thousand years, so it's natural that their bodies would have optimized in order to get the most out of that diet. And some cons, too, such as being more sensitive to a diet lacking copper and zinc, since the diet they became acclimated to was so high in it. Really no different from some humans who can tolerate cow milk(unnatural to humans), but most can't. How some people handle carbs or grains better than others.
So, in the big picture, I really don't think it has changed anything at all. Amylase is still a protein that turns starch into sugar, and then maltase breaks it down into a more simple sugar. Sugar carries little to no nutritional benefit at all, and these proteins aren't extracting any nutritional benefit from it. No minerals, no vitamins. If anything, sugar is converted to fat, and the dog's body would simply then burn the usable stand-by body fat in lean times, while still starving on a molecular level from the lack of nutrients. Common enough for a scavenger.
In no way would I see "oh, they can digest this, so they must NEED IT". I mean, scavengers can also digest rotting, vile meat. Do you think there's any nutritional value or need to feed your dog rotting meat? Probably not. They can have it, but it's not like it's any better for them to have it over fresh meat.
So I guess I really don't see how anything has changed at all, except maybe proving it, I guess.