Well, I have (admittedly this example is at the device side, not the plug side)
But if this had been at the plug end, I would not have been happy to find a soldered plug. Might have chucked it in the bin and got another one if that was the case.
To be honest, in this day and age of moulded plugs, it's getting pretty rare to have to wire a plug. But I stand ready to do so.
As for screws coming loose - you can always tighten them up. Not that I've ever experienced a screw come loose at a plug prong through basic usage. The cable grip, aye, occasionally.
Never hacked apart a moulded plug, hmm - might do that one day if I'm at a loose end