QA
It's a quality assurance problem. When writing code that deletes user files (due to age, being in the wrong place, whatever), the code needs to go through some extra quality assurance. I'm sorry Microsoft but if we aren't told that there is extra quality assurance that occurs when this sort of code is written, we can't trust your code. It's just not an option. They need to get this done and reassure us.
How they do this is really not our concern, they're the company we are all trusting with our computers. Sorry, I mean 'the computers that we are allowed to use by the grace of microsoft'.
Biting the hand that feeds IT
