The nuclear plants in Germany were too old and too expensive to maintain. At some point a reactor is just end-of-life. They get operational issues causing semi-frequent shutdowns. The reliability issues become a problem that skyrockets the costs further.
Closing a nuclear plant like that puts enough money back in the budget to afford a faster transition to renewables, which ultimately closes down the coal plants faster too. It’s about the big picture, it’s not as simple as simply saying “we’ll do less coal” or “we’ll do less nuclear”.