Honestly, I'm still baffled so many people were upset about getting a few album from a popular, well respected, rock band, simply because it found its way directly onto people's devices. It's not as if it woke you up at 3am and started playing it!
Well, you're looking at several phenomenon combined into one.
First, it's Apple. Apple is newsworthy. If you need ad clicks, mention Apple. Did I mention Apple generates traffic? It's at the point where I'm sure we'll see headlines like "Apple CEO Tim Cook Scratches Butt During Keynote" soon enough.
Second, law of big numbers. Let's say only 0.1% of people hate U2 to complain. Out of half a billion iTunes users, that's half a million people. It doesn't take much to think one of those people has a blog that's worth anything. And combined with the first, well, boom, all over the news.
Third, well, people only really complain when they have a complaint. If 99.9% of the people liked free music, they probably won't all post "cool, free stuff!" online. No, those people who have an issue with it "oh noes, free stuff, don't want!" will post all sorts of messages about it. Combine it with the first and second, and it explodes.
Hell, I'd expect if an error in a factory production line caused a fingerprint to be left on the screen it would be a massive national disaster. Even though one could easily just wipe the offending fingerprint off.