Apple’s customers trust the company with much of their daily lives. Sneaky promotions quickly erode that goodwill. See how things snowball in the eyes of the customer? An auto-downloaded album leads to them lamenting about small storage limits which leads to poor storage management systems… possible hacks…future distrust.
The right way for Apple to do a big U2 promotional deal like this would have been to simply make the album free on the iTunes Store for a while and promote the hell out of that.
Instead, Apple set everyone’s account to have “purchased” this album, which auto-downloaded it to all of their devices, possibly filling up the stingy base-level storage that Apple still hasn’t raised and exacerbates by iOS’ poor and confusing storage-management facilities. And when people see a random album they didn’t buy suddenly showing up in their “purchases” and library, it makes them wonder where it came from, why it’s there, whether they were charged for it, and whether they were hacked or had their credit card stolen.