Dairy consumption is not even the global norm because most people have lactose intolerance. Most Northern Europeans do not.
It very much is considered a vital part of diet in Norway, though, to the point where you'd pretty much be considered to be abusing your children if you don't ensure they drink lots of milk. While we certainly could survive without it, any politicians suggesting to Norwegians we should do without milk would find themselves out of a political career.
Just to point out, lactose intolerance exists at low levels in Norway. I wouldn't recommend ensuring that the lactose intolerant drink lots of milk just because it's part of the culture.
It very much is considered a vital part of diet in Norway, though, to the point where you'd pretty much be considered to be abusing your children if you don't ensure they drink lots of milk. While we certainly could survive without it, any politicians suggesting to Norwegians we should do without milk would find themselves out of a political career.