Users are creatures of habit who don't like change. Resistance (to change) is something I've written and researched extensively with users – people don't like to change even if it's good for them, because they are comfortable with how things are.
Apple wants to become part of user's lives, and the more they are the more likely that inertia will set in. The more integrated Apple products are in user's lives the harder it is to "break" from the "Apple way." They are "locked in."
In addition to a more integrated and usable experience, services like iCloud work best on – surprise! – Apple hardware.
Being an Apple "fanboy" (and shareholder) I look at this positively, because both parties benefit – users get a better experience (most of the time) and Apple sells more stuff.