Germany needs to stop feeling guilty. There's only a certain amount of contrition that can reasonably be expected.
Lessons have been learnt across the planet, nevertheless, history will repeat itself whether in the name of religion, politics or race - Srebrenica, Cambodia, Rwanda anyone? There will always be social stresses because there is always a section that feels hard done by, so open discussion is the only way to stop resentment becoming an uncontrolled problem as it is far more likely to lead to attempts at defusing the situation. If open discussion exacerbates a problem, then clearly it has not been responsibly discussed nor the situation addressed in the past.