Oftentimes it's done because it's cheaper, though oftentimes it's actually more expensive but they calculate that money from licenses post initial sale gets them more revenue and margin in the end anyway.

Still, even if it always was cheaper for the manufacturer this way, the point here is companies should not be able to control something you physically own once you have purchased it. It's a dangerous precedent to set and things like this will creep into more and more products if we let it.