It also means there's a cost to buying outside of the Apple ecosystem. I was downloading some previously purchased albums to a new device a couple days ago and couldn't find one in my "Purchased Items" that I knew I had purchased. Turns out, I had got it for half the price on Amazon a while back, but by the time I realized that, I wished I would have just paid the full iTunes price so that I could have re-downloaded it from iTunes like all the others.