Yes, indeed, dairy is very bad for human health. This is true for all animal products: http://www.forksoverknives.com/
Children wouldn’t want to eat milk products or any other animal products, if they knew how much slavery, suffering and death it caused to animals. See e.g. these movies: http://www.vegankit.com/why
Children much more easily understand the importance of living a vegan lifestyle. When we grow up, we continue to lose parts of our innate love and empathy, by sacrificing it at our meals and what is required in order to make these meals.
We need to extend our love and compassion to everyone. Everyone wants to live. If we hurt another being, we hurt ourselves. In order to kill someone, we have to violate this individual's love and wants, we have to crush hopes, destroy a family and friend relationships; We have to sacrifice part of our inner love and compassion; we have to say to ourselves that 'I don't care' in order to take someone's purpose and life. And this has destroyed us, destroyed our society. The reason why people inflict violence and suffering upon others is the lack of empathy and love to others. If we instead would reinforce love and empathy at each meal by living a vegan lifestyle, instead of destroying parts of our love and empathy at each meal by hurting and killing someone for 'convenience' or taste, we would surely attain world peace. As long as we sow violence and wars by our eating choices, our society and culture will be absorbed in violence and wars. How can we ever hope for peace as long as we inflict this violence and suffering?
Domestication of animals is a violence, it is slavery, and it also has resulted in human slavery, oppression against women, and other forms of oppression that is rampant in our society. Learn more in this book: http://cup.columbia.edu/book/978-0-231-15188-7/animal-oppression-and-human-violence#.UZAIageHrdk.facebook
As for replacements: There are many, for drinking, e.g. almond milk and rice milk. For cooking, coconut milk is very, very tasty. Dr. Neal Barnard refers to research which says that our taste buds is renewed within some weeks when we change diet. But even if there was no replacements, there still would be no justification of inflicting suffering and death to our precious sentient and feeling non-human brothers and sisters.
Hope this helps and motivates you to transition to the lifestyle of non-discriminatory love, compassion and nonviolence to everyone who is consciousness!! :)