It's way more expensive than coal, wind or solar. And since the German government doesn't seem to subsidize anything except coal, nuclear has no chance.
Risks had not been factored in as likely (like in Japan the authorities have demanded protection against earth quakes and tsunamis, but only to a certain level and they were surprised to learn that over the lifetime of these plans stronger events happen than anticipated) and if anything happens, the companies are simply not insured - other than via the government, which had created the demand and the environment for these reactors. The companies are also not well prepared if larger accidents happen.
Example: Many old reactors never were designed to withstand an impact of a large passenger airplane.
Large passenger airplanes don't fly into buildings. Right? Well, we have learned in the meantime that this scenario is not that unlikely, since 9/11 and for example the Lufthansa/Germanwings pilot, which flew an Airbus into the ground in France killing all passengers on board.
One could now just let these old reactors run. What to do with the risk? Well, set up military systems to shoot down aircrafts approaching a reactor site? Adding more concrete as a protection? I'd guess that there were some clever people exploring the options and in the end its just to costly to do something working...
That's extremely easy to explain. They are expensive and therefore nobody wants to be the scapegoat that is responsible for hundreds of billions of lost tax dollars unless a convenient event like Fukushima offers an excuse.
