I have heard arguments by the American Dairy Association (who admittedly has a huge stake in the issue) that "milk does a body good", suggesting that milk is an essential part of nutrition and should be consumed (in some quantity) each day.

I have also heard that, in fact, milk creates many allergies and, actually, has proteins too complex to truly provide good nutrition for human beings.

What are the true facts? What is the truth about this "Dairy Hysteria"?

yes, much of that is true.
there is really no health reason why adult humans need to drink milk- whether cow´s, goat´s, or mama´s. however if you have no problems drinking/digesting milk, there´s no reason not to drink it.
you can get the same vitamins and minerals from other foods just as easily.
i personally cannot digest the milk sugar, lactose if i have more than say a cup of milk.
i love to drink coffee and cappuccino, but i buy lactose free milk, which is a little expensive, but i have no other problems with milk.
hope that helps!