At the time pasteurization came into effect people were regularly getting sick from consuming milk. This was both because cleanliness was nowhere near what it is today, and refrigerated shipping was still in its infancy. Heating milk to kill bacteria, then sealing it until it could reach the consumer was a tremendous boon to public health.
It continues to be practiced because cows don't take baths before they get milked.
At the time pasteurization came into effect people were regularly getting sick from consuming milk. This was both because cleanliness was nowhere near what it is today, and refrigerated shipping was still in its infancy. Heating milk to kill bacteria, then sealing it until it could reach the consumer was a tremendous boon to public health.
It continues to be practiced because cows don't take baths before they get milked.