ec - just as a reminder, Boeing introduced MCAS (in part or in whole) to allow the MAX to fly and "feel" enough like previous 73s that it would not require crews to go through special training in transitioning to the MAX.
And that was a selling point to customers, not just the regulators.
Word on the street is, Boeing gave, e.g. SWA, a $1-million-per-aircraft "performance guarantee" that no sim time would be required to transition from NG to MAX. Just "iPad ground school."
A software patch connecting existing hardware (AoA sensors, trim system, THS, flaps) was the cheapest and easiest way to do that. Especially without screwing up "normal, everyday, straight-and-level" stability and handling.
(That's not a defense of MCAS, just an explanation).
Purely from the point of view of preventing a CFIT or a stall, modern planes already do have equivalent systems - audible warnings so that the pilots can correct things themselves. "Pull up, TERRAIN" vs. "STALL, STALL (rattle-rattle-rattle)."
Of course, if the RAs fail or the AoA sensors fail, the systems fail.