This is entirely unsurprising if you actually look at things other than big CPU/GPU/IO.
Power regulators doesn't need small transistors, it wants big nice and fat transistors. You'd get at least one of them in every device and a bunch in any bigger device. Same with any power device, LEDs, and really anything that passes some current.
Any microcontroller smaller than "runs full fledged linux" often cares about cost of production first and foremost, hell, STM32 only recently [1] got on 90nm node!
Interestingly enough, bigger node might get you worse uA/MHz but often lower idle current (the bigger things are the lower the leakage) so they might even be desirable. And the chip might want to have some mA current output on each pin (so it doesn't require external drivers to control stuff), which again means some transistor size in your I/O port is fixed and can't be made smaller so your savings from going to smaller process are not linear.
For vast majority of non CPU/GPU chips it comes to cost to manufacture and those 20+ years old lines not only paid for themselves multiple times, they also have great yields.
* [1] https://blog.st.com/stm32g0-mainstream-90-nm-mcu/
Power regulators doesn't need small transistors, it wants big nice and fat transistors. You'd get at least one of them in every device and a bunch in any bigger device. Same with any power device, LEDs, and really anything that passes some current.
Any microcontroller smaller than "runs full fledged linux" often cares about cost of production first and foremost, hell, STM32 only recently [1] got on 90nm node!
Interestingly enough, bigger node might get you worse uA/MHz but often lower idle current (the bigger things are the lower the leakage) so they might even be desirable. And the chip might want to have some mA current output on each pin (so it doesn't require external drivers to control stuff), which again means some transistor size in your I/O port is fixed and can't be made smaller so your savings from going to smaller process are not linear.
For vast majority of non CPU/GPU chips it comes to cost to manufacture and those 20+ years old lines not only paid for themselves multiple times, they also have great yields.
* [1] https://blog.st.com/stm32g0-mainstream-90-nm-mcu/