When you increase the number of moving parts in a machine, you also increase the number of ways in which the machine can fail. As a rule of thumb, simple designs are more reliable than complex ones.
Our modern microprocessors are fast and powerful, but unlike older transistor-based designs, they are extremely susceptible to electromagnetic interference. Electromagnetic pulses (EMP) caused by nuclear explosions can cause destructive voltage surges that could ruin most electronics.
Our over-reliance on technology is a liability, and our culture of mass consumption complicates matters even more. Several industries, such as the consumer electronics industry and the automotive industry are built on the principle of planned product obsolescence. Products are not made to last for decades. They are made to break or become antequated after a number of years, so they can be replaced by the consumer. Many products are not even made to be repaired. If products lasted forever, manufacturers would go out of business and lay off all their workers.
It is said that Henry Ford once visited a junk yard filled with rusty old Model T's, and took a long look at one of them. He observed that the axles were still good; the axles had outlasted every other part of the car. He then decided not to make every other part of the car as sturdy as the axles, but instead, to put less steel in the axles, so that they would fail at the same rate as the rest of the parts. So we get a new car every few years, because of planned obsolescence.
In the Soviet Union, where corporate profits were not the goal, they would build things to last for a long time. Manufacturers would come up with a good reliable design, and stick with it for years. The goal was to ship units to far-flung corners of the country and make sure that Siberian farm boys would be able to fix them with rudimentary hand tools. So they made their designs simple and reliable. One such example was the AK-47 rifle. You can drive a car over one, bury it in the mud, throw if off a cliff, and then pick it up, and it still fires. In the words of a former special forces soldier (sorry I don't remember his name, only that it was during a TV show on the Military Channel), "If you want to maroon me on a desert island away from civilization, and I can have only one firearm with me, I'm picking an AK."
During World War II, a remarkable vehicle called the General Purpose Vehicle, also known as the GP or Jeep for short, was designed for the US military. Again, the emphasis was on reliability and ease of repair. Soldiers stuck in some muddy battlefield somewhere had to be able to fix it and replace pretty much any part on it using just tire irons. How easy was it? Just watch this demonstration by a Canadian Armed Forces unit during a parade in Halifax, Nova Scotia: