I disagree. Being kind is a virtue. It makes up a persons character. Being nice is an attribute of pleasant society. It yields passive aggressive attitudes and permits micro aggressions. It’s a show of civility to reflect kindness while enabling self-righteousness and hiding true feelings. 

For example hiding one’s true opinion to maintain a pleasant atmosphere is nice. Withholding honest feelings while plastering a smile on your face to not cause a problem is nice. Pretending to enjoy something that is displeasing, offensive, or lackluster is nice. Empty compliments and sweet words are nice. 

Being honest is being genuine. You seek to tell the truth without hurting the recipient of the action. It yields understanding, empathy, and compassion. It enables joy. It’s telling the truth and/or finding the truth. It can be humiliating at times but that builds character. 

I don’t cut people out of my life easily. I protect my peace by paying attention when people show me who they are. Then I move accordingly.