80% of accidents are due to pilot error. Always have been and, apparently, always will be. A mechanical defect might be the initial cause, but in most cases a competent pilot can still safely fly the airplane to a landing. Runaway trim is not limited to the 737 it can happen on any aircraft with electric trim and there are procedures written to correct this fault that any pilot who deserves to be appointed as PIC should know and be able to implement. With the degradation in pilot skills we see happening in every country now, due to the shortage of trained pilots, we should expect more of these types of accidents.
Blaming the aircraft does not help. The ability of a manufacturer to make changes to the design is restricted due to tort pressure/regulation inertia and unlikely to happen, even in this case. If a design is changed there will be multiple court cases saying "See? We told you the design was bad!"
The days when we could expect a normal crew to do a normal job are almost gone. The newbies are not taught as well, are not as experienced when taking the left seat and apparently are guilty of not knowing what they do not know so will continue to fall behind in competence, leading to an increase in pilot error accidents.
It is a different world we are entering. Get used to it.