Error -54

"App Thinning": In order to make apps smaller with iOS9 they are being customized for the specific hardware on which they are to be used. For example the variant of an app downloaded for a retina iPad may not be suitable for a non-retina iPhone. You transferring from one device to a computer to a different device may result in the wrong version being used and Apple has disabled transfer from device to computer in order to prevent this happening. If you want a backup copy on your computer you can transfer a non-thinned version directly from the Store to the computer which should you need it can be transferred to any i-device (but will take up more room).

https://developer.apple.com/library/watchos/documentation/IDEs/Conceptual/AppDis tributionGuide/AppThinning/AppThinning.html - iOS9 App Thinning > "Slicing is the process of creating and delivering variants of the app bundle for different target devices. A variant contains only the executable architecture and resources that are needed for the target device." ... "The App Store will create and deliver different variants based on the devices your app supports."

== Error -54 ==

From an OS9 reference, error -54 is a software lock on a file or a permissions error. (Although there is no formal list of OSX error code some of the old codes still apply to OSX .)

First, try simply restarting your computer.

Try quitting iTunes, then deleting the .xml (not .itl !) version of the library file in the iTunes folder (iTunes will generate a new one).

iTunes Library cannot be saved (Error -54) - https://discussions.apple.com/thread/1912814 - various things to try.

Error -54 possibly related to Touch Copy - https://discussions.apple.com/thread/3727114 - cleared by deleting preferences on iPad.

iTunes: Missing folder or incorrect permissions may prevent authorization - http://support.apple.com/kb/ts1277

Troubleshooting permissions issues in Mac OS X - http://support.apple.com/kb/HT2963

"Unsupported" effectively means as if they no longer exist and as if they had never existed. They have been completely expunged from the corporation memory. Go to an Apple Store and mention you own one and they will look at you like you come from another planet. They will look for the oldest person in the store who may vaguely remember having used your "unsupported" device in grade school. 😀 I am not kidding, do not expect any consideration for using unsupported devices. (I have never owned anything except unsupported devices and you are completely outside the Apple corporate support sphere when you do so. By the way this is a user-to-user forum, not an Apple to user forum. 😉)

What is okay or isn't is not the issue here. Apple does what it does. Unless you can start a mass boycott of Apple products because they disabled this feature I suspect there isn't any other way to convince them to do differently. Oh, you can send feedback to them but dropping support after a period of time is a fact of life for modern technology ownership -- everybody does it. As I said before, if the topic involves unsupported items it is a non-starter as far as Apple support is concerned. By the way, this is a technical support forum and starting discussions about Apple's policies will get posts/topics removed.

You say, "Everyone is complaining." I am not seeing this. I have seen a couple of people mention it here on this forum, compared the probably tens of millions to whom it makes no difference. It is like going to a hospital emergency room and saying there is a mass outbreak of broken legs because you see other people there with broken legs.