Samsung, Blackberry, Nokia, Microsoft.... they all had money for R&D and time.
>_< accept it, apple is not a shining light.
and relay apple is 100% where they want to be in the market, there raking in the cash... raking it in.
most there users get what they want, they dont need or know what there cpu is past it's mhz and maybe number of cores.
if you can go to facebook, buy shoes, watch youtube, light productivity apps (Microsoft office etc), skype, emails, mate it with your phone play music & netflix then you provide what most users want. ie consumers
the imac updates has had a lot of nods towards the indie video production segment with it's display updates.
but we may never see things like the apple avid cooperation like we did in the past
https://en.wikipedia.org/wiki/Avid_Technology
& from a pro perspective you want a system that is stable and works, constant updates are for enthusiasts.
I know people in the video land that upgrade the system once a generation of video (ie SD->1080p->4K)