Comment by mrheosuper

and it comes with new set of problems: Now you need a FW guys to write and maintain software for it, then your hardware team may need to wait that FW guy to release software to test, or the FW guy need to wait hardware to test his software, etc.

Then in production, you need another stage to flash the FW, which add time and complexity.

Then security, cheap MCU usually has bad software protection, that means your software can be read out easily, not a big deal since the FW replacing the 555 would be dead simple anyway, but try to explain it to a non-technical CEO when he read about it on his morning's newspaper.