No new nuclear power plants since 1989. Peak electricity grid contribution by nuclear power plants: ~30%, while oil and natural gas were used for heating (so replacing that with nuclear power means doubling NPP output, roughly). So Germany still would have had to increase its nuclear power plant capacity 6-fold to go all in.
Compared to France (70% from nuclear power, natural gas for heating in only ~1/3 of homes) this hardly looks like leadership.
As for the reasons: There has been a series of events where nuclear reactors weren't properly handled and where politics colluded with the operators to sweep it under the rug. No matter how safe the technology _could_ be, its management was horrendous.
One such example was a "passively safe" reactor that by now is a glowing mess for 40 years already, and will remain so for another 60-80 years before it can be dismantled: https://en.wikipedia.org/wiki/AVR_reactor
Key quote from that Wikipedia article: "The report listed hidden or downplayed events and accidents and described serious concealed problems and wrongdoings. For example, in 1978 operators bypassed reactor shutdown controls to delay an emergency shutdown during an accident for six days."
As long as people argue about the merits of the technology, they miss the German discourse on nuclear power completely.