This isn't surprising to me at all. I have friends who are still on iOS 7 because they don't have enough free space available to upgrade. When I tell them they can upgrade by connecting their phones to their computers, and thus, doing it through iTunes, they look at me like I'm crazy, or like it's 2008 or something.
I removed half of the apps on my ipad to update it to iOS 8 ... I am not sure it is even possible to update to iOS 8 through itunes. There does not seem to be an iOS interface anymore in itunes.