Given that MCAS is a system to minimise the additional lift at higher AOA's from the larger engine nacelles which are further in front of the wing (giving a greater moment arm), would a MCAS activated nacelle spoiler not achieve the same effect? You're eliminating the problem at source whilst retaining full control authority.
It's an aerodynamic solution to an aerodynamic problem, MCAS re-programming is minimal, you're using the same values but different implementation.