While difficult to prove, in all likelihood Apple is probably deleting files from computers to increase sales. I would not put it past any company to undertake such a venture to try to increase sales, especially in hyper-competitive markets like the PC, computer and laptop industry where customer preference is huge.
True that ; I don't think Apple should be worried to lose the business of potential terrorists so actually they only are worried about their face. 99.9999% of the users of an iPhone or iPad do not need any form of protection except against theft so the thief won't be able to see their selfies in the bathroom or read their dirty chats with their mistress. We only have to worry about the way they store our data which is more than often compromised and then everything is on the street (think the Ashley Madison hack) and no super-secure unbreakable iPhone is going to prevent that.
I am not aware of Apple deleting files from computers to increase sales. The idea that deleting files from computers would increase sales for Apple is confusing and does not make sense. Is Apple deleting files from customers computers? For what purpose? How would this increase sales for the company?
No, they are not deleting files to boost sales. Although they could because if you read their terms of service, they own the files, not you. However, Apple would not just starting deleting files as nobody would use their services if they were found out. It is a bug, plain and simple. They already have info on what you have downloaded to your library anyways so it's not like they can't easily replace them.