People who exalt niceness above everything are usually the fakest and meanest. Niceness has no integrity! It's often false appeasement, suppression of truth. Kindness and thoughtfulness are real tangible things though. & sometimes goodness and niceness cannot stand together.

Also think about the way niceness has always been weaponised in both gender and race relations. The notion of the Cult of Womanhood was hinged on nicencess and helped form the conception of white womanhood (genteel, soft). Its foil is stereotypes such as The Angry Black Woman.