My kids go to an Ananda Marga school. No eggs, meat, garlic or mushrooms. Many members are vegan. No dairy there and they are all healthy little tackers...
It is our societal norm that we eat dairy food. It is not a nutritional fact that we need it.
People live their whole lives without it. Whole countries live without it.

I think it's healthy to question anything that "seems" normal or okay. It's kinda like saying we all need red meat. We don't! Or we all need 8 hours sleep a night - we all don't!