What it comes down to is that there is a copious amount of research being done that states grains in this day and age are absolutley terrible for your body. Not only are they toxic but, they have no GOOD qualities. They are empty calories. it's like if all you ever ate was water....with poison in it. If you really want to look into grains, read or google the book "wheat belly". It will explain everything.
Even then, there are so many studies done for and against both sides. Its hard to decide who is right. There are always flaws. For example, your study about people with high fat diets having heart attacks. It says high fat diet, it doesnt say high fat low carb diet. You can't do both. It also doesnt say what kind of fat.
You just have to do some critical thinking and come to your own conclusion. For me it was simple. Humans are meant to eat meat and vegtables and fruit. MAYBE they were able to eat grains, but todays grains are NOT yesturdays.