And thats the kind of thinking that causes problems. Just because bones are made of it does not mean we need to take in excess. On the contrary, excess causes big problems, especially when done without getting the various other nutrients needed.
Calcium does not just goto bone by itself, it requires other cofactors to get there. Without the other cofactors the calcium doesnt goto bone, it calcifies joints and arteries causing problems.
So, milk in moderation isnt a problem, preferably fresh from the farm. But when you start drinking a glass a few times a day you are undoubtedly getting much more than you need and causing problems.