For loading .ipa files onto iOS devices, I have generally switched to using CopyTrans (not iTunes), as I wrote here. However, ever since iOS 9 (per ), the only way to get those .ipa files was through PC iTunes. iOS 9 removed the ability to transfer .ipa files onto a pc from apps already loaded onto an iOS device.
I have periodically had a need or desire to load an earlier version of an app, when some aspect of the current version wasn't working the way I wanted. Less than a month ago I so reverted Opera Mini to the earlier version 14, since the new version (16) forcibly includes a bunch of mass-market web articles, which I don't want. (Reverting conveniently fixed a space-rendering problem when viewing various websites [though notably not Google News], a problem which started perhaps a few months earlier, and which I'm guessing was due to some Opera Mini data corruption on my iPod.)
I don't think Apple is likely to ever reverse this change, so I'll be staying away from iTunes 12.7 and its successors as long as possible.
9/21/17: Apple still provides access to pre-12.7 iTunes installers for Windows (search for "itunes" on https://support.apple.com/), but that could change at any time:
- If you deinstall a 12.7 (or later) version of iTunes, and replace it with a pre-12.7 version:
- You may have to sacrifice the data in your My Music\iTunes\iTunes Library.itl file because the earlier version of iTunes may not (probably won't) work with one that has been modified by a 12.7 or later version of iTunes. How much that file's contents matters to you depends on how you use iTunes. You may be less dependent on it if you use third-party software (e.g., CopyTrans, which I wrote about here) to manage iOS device(s).
- You will want to avoid upgrading it when you get apparently periodic prompts to do so from the Apple Software Update software. I don't think there is a setting via which it would automatically upgrade to a newer version without prompting for your approval, but if there is, you will want to disable it.
- Depending on the model of your iOS device(s) and/or iOS version(s), a certain version (or higher) of iTunes will be needed to manage it. If you had 2 (or more) PCs, you could manage your device with a 12.7 or newer version of iTunes on one PC, and use a pre-12.7 version on a different PC to download .ipa files.