Otherwise the costs would explode. This is why products are designed to fit as well as possible to some average person that very often doesn't even exist in reality. Afterwards it is the job of the marketing division to convince all people that this product is made for them especially and they should buy it because it'll make them happy. They create piles of bits and bytes that are being sold to the customer - suggesting that just the possession of this pile will solve all the problems. The actual reason for this concept, the machinated mass production, does not exist in the virtual space of software, though.
Software can be custom-fitted to the customer in a way no other product can.
Trapped in old patterns of behaviour they have been applied although the necessity vanished long ago. For this reason business models for Free Software concentrate on problem solution instead of declaring possession the solution. And that is why the discussion of property rights is irrelevant. In fact it is preferable to the customer if the software is not owned by anyone - neither him nor the company that he got it from. The value of software is very much determined by the amount of maintenance that goes into it - without this service software loses its use very quickly.