Stats show and tell it all. 

CNN Study
shows that 94% of all iPhone users will buy another iPhone while only 47% of the Android phone users.

I personally think the connection is emotional with the iPhone while pardon the pun but robotic with Android.   Android while a great enabling technology and useful in every way.  The iPhone connects at a deeper more human level….emotional level.  People love I mean LOVE their iPhones.

I believe it’s with subtle shadowed 3D look of the graphical elements but moreover it’s the human like movements that seduces you to have all that warm and fuzzy feeling when using it.  Makes us more forgiving of all its imperfections and idiosyncrasies.  Just as if it was your favorite child.

Android seems although very useful but cold and utilitarian so dispensing with it is easy compared to the iPhone.

Thus iPhone pulls you into this trap of wanting another.   Because one thing Apple makes sure you get is the same experience but better not different.  One could use the original iPhone and use the latest and still be able to fully utilize it because of the consistency of the User Experiences.

Android for whatever reason wants you to enjoy new experience with every version not consistency and maybe stagnate like the iPhone.