In a world where most people don't have unlimitted data, that is a big deal. If I'm going for a long drive, I can rent a movie on my Android device from Google Play, download it before we leave the house, and my daughter is happy the whole way. If I had to stream the movie, I just wouldn't even rent it in the first place. I really like Windows Phone and want to come back to it from Android. However, it is details like this that keep me from making the switch. Little things add up. I'd love to get a 1020 or a 1520, but there are just too many little consessions (some MSs fault, some not) that I would have to make that add up to a big enough reason not to switch back.
Windows Phone users shouldn't write off these little short comings. They should put pressure on MS to bring their OS up to par with its competitors.