I used to serve juice.... when my oldest kids were little, it wasn't such an issue. It was totally normal to give them juice.
I don't let them drink anywhere near as much anymore. And the dc kids only get it as a special treat, on "party" days. You don't realize how much sugar is in juice (even 100% real, as it has naturally occuring sugars) until you give it to 6 little kids!!
And; to play devil's advocate here... in regards to the comment about humans being the only mammal to drink another species' milk? We are also the only carnivorous mammal that does not eat the bones of it's food, thereby taking in the various nutrients that would provide. Milk gives many of those things to our body. But I do agree that the milk we buy off grocery store shelves is not nearly as "healthy" as it used to be. Too much stuff added/done to it. Scary.