The ability to change features, prices, and availability of things you’ve already paid for is a powerful temptation to corporations.
It doesn’t need to have been a noble goal to be a noble result.
For something to be actually and reliable preserved and win against random decay, data loss, disaster, and whatever else will statistically destroy copies, a thing will need to be stored by at least thousands of people. But there is no way to know how many, only that you increase the likelihood of perseveration by storing a copy.
I agree, most people are downloading a thing because they want it. But by keeping that thing, they are also preserving it.