I am a recently retired dairy farmer and have drank milk every day for the last 68 years! Oh I so agree, QuiltE; your definition of milk is spot on. My particular grief is why is milk sold by fat percentage and not by its fat free designation; ie whole milk is 96.5% fat free, 2% is 98% fat free. And look there's only a 1.5% fat difference in the two! My little soap box.
And yes there are folks out there allergic to lactose (the natural sugar in milk) and how unfortunate it is that they miss out on all the wonderful vitamins and minerals found in milk as it is a very nutrient dense food.
In regards to the Vitamin D issue. Vitamin D is a fat soluble vitamin (as is Vitamin A); in other words only carried in fat. If you take the fat out, you also take out the Vitamin D!