In fairness, China's southern and western provinces have historically been on the shorter side. But also, like.... Yao Ming.
90% of the population is lactose intolerant
You can improve lactose tolerance if you introduce milk to kids at an early age and drink it continuously. My 50s-era Jewish family are all horribly lactose intolerant, but I grew up chugging the stuff and do just fine with it. Plenty of ABCs can and do drink milk and eat dairy, just as a matter of living in a country so full of cows and cow-products.
What happens in another 20-40 years, as we obliterate our grazing lands and drive the cost cow products skyward? Idk, man. But milk is a consumer staple for a reason. Calorically dense. Very useful in cooking/baking. Relatively cheap to produce and distribute. Goes well over cereal.
If milk did not exist, we would have to invent it.