The complexity of software is making for insecure systems and slowing down the improvement of that same software.
Consider iOS and all the frameworks present in macOS. The two are cousins - as if macOS was the United States and iOS Great Britain. Move from one country to the other and you feel you know the rules but you step out into traffic and are nearly killed because the vehicles were coming from the “wrong” way.
Logically there would be a way to smoothly shift from the older, more complex, macOS implementation to the more modern iOS. But in doing so fundamental features would be lost that make the Mac what it is. The restrictive nature of the original hardware on which iOS was designed to run for the most part no longer hold. (watchOS is an exception.)
Both of these systems came from designs by NeXT in the last century.
It’s time to ponder a redesign of the OS with an eye to efficiency of implementation and growth and security.
I argue that Apple can do this and must do this for its products to continue to evolve.