Powdered milk has been heated, so some of the fructose has caramelised – altering the flavour.
Coffee makes had the same problem 15 years ago, and started freeze drying the liquor.
What you actually do, is reduce the pressure. At 1 bar of vacuum, even water at 0oC will boil. And vacuum is cheap to produce
P=0.1 bar, so the energy is very low.
So we do the same to milk. The water boils off. Part way along, we have the constituency of cream. Massively cheaper, and more healthy than cream.
Taken to the limit, we are left with a powder. That does not require storage at low temperature. We add a table spoon to tea or coffee – and the taste is like fresh milk.
The transportation and storage costs are massively reduced.