'When machinery is under manual control, it should be under manual control. There is absolutely no reason at all for this system to automatically control the aircraft.'
Except Boeing had no choice if they wanted the aircraft to be certified for flight. In essence on previous 737s as the aircraft approached the stall, think ~15-20 degrees nose up, the loss of lift from the wing coupled with the centre of gravity being ahead of the centre of lift caused the nose to fall recovering the aircraft from the stall. In trying to put even bigger engines on the 737 they had to move them forwards and up, this created an interesting aerodynamic effect where as the stall was approached the pods start to generate lift which counters the natural nose down tendency. In other words rather than naturally recovering from a stall the aircraft would now naturally enter one at high* angles of attack. This could lead to an irrecoverable stall and death. MCAS is designed to stop the nose getting too high and making the aircraft fly more like a legacy 737.
Before you say it's automation gone mad, the Hawker Siddeley Trident from the 60s had a stick-pusher to prevent it entering an irrecoverable stall. Because why let people put the aircraft in a situation where it definitely will kill them?
*it's high for an airliner