Follow the money. I suspect that the biggest reason we have so much promotion of “low fat” milk products is because the processors get to take the fat out and make cheese, then sell you the refuse at the same price you pay for whole milk.
Another part of the studies that will change in the future (after a lot of people get genetic testing done) is the number that are lactose intolerant. I suspect there are millions who didn’t know until recently, like me, and fought with various pains, gut issues, etc. because the doctors we usually get are treating the “statistical average” and if you’re not dying, there’s nothing wrong with you.