I can probably guess with a good amount of certainty, that Apple doesn't like anyone stripping their phones of features, especially not security features which enable things like ApplePay, and they definitely don't like unhappy Apple customers.
Yup, exactly.
Some people don't understand why other people pay a premium for Apple products. So, they attribute it to stupidity, marketing (also stupidity), or being sheep (again, stupidity). They ignore what is obvious to a lot of happy Apple customers, Apple does a lot to keep their customers happy, because happy customers pay a premium for Apple products, over and over.
Do Apple products have problems sometime? Yup. Does doing something other than Apple intended sometimes seem more difficult than it should be? Yup. I still think I've come out ahead on time and frustrations. If you don't like my choices about such things, well, get a life.
As for Apple just wanting people to pay for first party parts because they are greedy, maybe, but I've also had Apple replace third-party memory and storage in my laptop for free when doing a paid repair on another part of the system. Oh, and there was the time an Apple store they declined to try to help a friend's girlfriend get data off the damaged HDD in an old iMac that had been damaged in a house fire, but they sent her home with a new iMac, no charge.
Oh, and the idea that this couldn't be about security because it didn't happen until over a year after the iPhone6 first shipped: ignorant and foolish. The security landscape is always evolving and changing. New threats emerge. Evolving defenses limit the ROI of people developing and deploying exploits.