The margins on selling the OS were never very good. Apple has always made the majority of their money from hardware sales.
Where is this case? In my experience, something I saw online simply wasn't available to me, like AirDrop, for instance. I upgraded my mid-09 MBP to 10.7, looked for AirDrop and couldn't find it.
Same for Handoff and the Bluetooth-required new features in Yosemite. Apple doesn't go out of its way to inform me my hardware is out of date; features talked about in the media are just missing.
edit: Also, your post sounds dangerously close to the uninformed "Apple purposefully makes iOS n perform worse on device x", as if that's a smart business move.
Given that, it makes me wonder how the unmodified Mac mini and MBA perform.