If you have an iOS device and sync with a desktop Mac regularly, you may notice your Trash bulge. Though in the almighty Commonwealth we usually refer to such a refuse containment device as a “rubbish bin”, thank you very much.
With each sync, upgraded iOS applications have their older versions placed in the Trash. This respects the standard OS X development model of never deleting files from the GUI, but moving them to the Trash instead. Still, when it first happened it took me by surprise, especially given its coming from an external device.
Naturally, I archive all of these. I’ve got ipa files going back to my first iPhone 3G in 2008, neatly catagorised by month and function. Because the difference between a hoadrer and archivist is organisation.
It also serves as a useful alternative source for those apps that were since removed from the App Store. Not that you read that, you bird flapping DOS Commodore emulating VLC 1.0 person.
If you have the space, consider doing it too. Who knows, years from now you may get an old iOS device and want to indulge in some nostalgia. Though I suppose by then all our apps with web back ends would be long since broken, ala Sherlock.app from Mac OS 8. No, not that Sherlock.app.