The only reason this works is that it's backed up by government enforcement of intellectual property rights. If the government didn't do that, then consumers wouldn't pay anything for office software, Microsoft Office wouldn't exist, and the whole landscape would be very different. The natural price for the second copy of a piece of software is $0.
Something being known and taught in product classes doesn't make it any more acceptable. Planned obsolescence is taught in economics classes, and it's still awful despite that.