The dairy industry is cruel to cows, but milk is probably not that unhealthy to humans. Also, I don't get the argument that I always see on vegan pages that milk is "not necessary." Of course milk is not necessary in the human diet, but neither is any single food item. Neither rice, nor wheat, nor soy, nor orange juice is necessary. Milk is, however, a convenient source of protein and calcium. The relevant point, however, is that milk (meaning dairy milk), despite being a convenient food source, is produced in a way that causes suffering. Dairy cows have their babies taken shortly after birth, are often abused, and are sent for slaughter when they're no longer sufficiently productive. So, despite the usefulness (though not necessity) of milk and its derivatives (cheese, etc.) in the human diet, and despite the fact that some of these products taste good, humans should begin transitioning away from consuming dairy. Soy milk, in particular, is a near perfect replacement for dairy milk, without the cruelty. Soy milk fortified with calcium is nearly nutritionally identical to dairy milk. Most of the other plant milks besides soy have very little protein and do not pack the same nutritional punch.