I am sure everyone loves the higher speed of file transfer that the iTunes Files-Sharing provides. Many people were pushing for it because Files didn't have the capability before. On the other hand there was no major problem with file protection previously so I am not surprised that you didn't get too many queries. It doesn't mean that people would accept trade off on Files security over speed. I believe many of your users are probably not even aware of this newly introduced security hole. So I hope you don't assume that it is fine to leave that hole wide-opened when you advertise that your product provide file security.
In spite of the problem, I still consider Files a useful product and I took time provide feedback hoping that you guys would make it even better. I had never ask for refund so I am not sure why you made that suggestion and what your motives were.