This rise in complexity is in part due to the pull of rapidly advancing digital electronic technology. Compute power is so cheap, it becomes the optimum way to provide what the customer demands: performance and economy. And customers do demand ever more performance and economy, whether it's due to constraints or worries about the environment, or just because it's what they're conditioned to expect by automotive advertising.
Improvements in safety and efficiency seem entirely positive, but if the cost in complexity brings new risks from rare but catastrophic failures, the gain is not so entire. If 95% of customers have an improved experience, but 0.1% suffer dreadful consequences, the trade-off is not obviously worth pursuing.
But if manufacturers of such complex but safety-critical products could more effectively address the risks of rare but catastrophic failure, so the failure rate could be reduced dramatically, the gains in routine safety and efficiency could be enjoyed with much less risk.
One important such mechanism is already in widespread use in the airplane industry: the black box. It may now be time for the introduction of black boxes into automobiles. Something like a flash drive could record perhaps a half hour's worth of data - the movements of the steering wheel and the pedals, together with engine and wheel speeds, at the very least. Key data from various subsystems should also be included - whatever information could best help engineers diagnose the cause of whatever catastrophic failure might occur.
There are also tools available to help designers find and fix rare design flaws, so they never escape to the field to cause failures. But it is unreasonable to expect activities like driving cars and flying airplanes to be perfectly safe. Reality always has more tricks in reserve than any design team can anticipate.
While engineers certainly must work diligently to eliminate flaws, the real key to progress is to learn from whatever failures occur despite one's best efforts. Modern cars have become so complex that the gross evidence of tire skid marks and observers' memories are insufficient to enable diagnosis of rare failures. Black boxes in automobiles could provide an economical and effective way to learn from those failures so the problems can be fixed before more lives are risked.