It seems that every recent iOS update turns Bluetooth back on if you had previously disabled it. Why would Apple do this? Kashmir Hill of Forbes proposes that the answer has something to do with iBeacons. follow link
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Why Apple Keeps Turning on Your Bluetooth
I have spoken with a developer who could not comment but would say that "we were doing what the design specs called for."
For whatever reason, Bluetooth is being enabled after each IOS upgrade I concluded that it was/is a conscious decision by Apple. To what end I do not know. Are there any other preferences or hidden features they are enabling that we are not aware?