Dingbatt: Except the fact that MCAS is to remedy a dynamic problem caused by differently positioned engines compared to previous versions. Ballast will only fix a static load problem to adjust the balance of the aircraft. Normally only used in smaller commuter aircraft as a last resort.
Imagine having a car that always pulls to the left, as part of the design. Software corrects that. You need to hope the software never fails, and if it did, you werent in a precarious position next to the white line at high speed, etc. An aircraft runs in a 3D environment, massively more problem situations if it failed