Leaked emails indicate, they use iMessage to actively lock down users in their walled garden. This is area with literally zero innovation (or even regression) for past decade. At least.
Giving money to Apple basically equals to strangling innovation in exchange for getting (sometimes or even rarely) marginally better UX in boring, well explored areas.
Also once you are bought into their ecosystem you are stuck with some mediocre products like iPhone, because if you want alternative, you have to throw away watch, tv and speakers and then redo entire home automation due to lack of elementary interoperability.