When I was a senior in high school, we voted on each other for categories like "Most Likely to Succeed," "Most Athletic," etc. I think there were about half a dozen of these awards handed out. In the end, I was voted "Most Considerate." (Side Note- My wife was voted "Friendliest" in her senior year.)
I didn't really view myself as considerate. Inside my head, I thought plenty of mean things about people. I was/am incredibly sarcastic and cynical. I just rarely said what I was thinking or feeling out loud. Some people might think that's because I was being considerate of other people's feelings. I get it. But I think it had more to do with fear.
The definition of considerate is "careful not to cause inconvenience or hurt to others." I read that as "don't make waves." Of course that is not inherently a bad thing. Considering other people's feelings when sharing is an essential skill. I'm more concerned with how 'being nice' can also be a mask for being afraid to speak truth. It's cowardice dressed up as nobility.
Sometimes 'being nice' can mean being dishonest. The Latin root for the word nice means ignorance. It can mean I am more concerned about what the other person thinks about me than I am concerned about their own well-being. If that's the case, it actually prevents intimacy. Under the guise of 'being nice', we can settle for the shadow of a deep, honest, caring relationship.
Of course, I'm not saying that we should stop being nice and start being mean. I'm not saying be intentionally hurtful. But maybe there is another path. Paul says it like this: "Speaking the truth in love, we are to grow up in every way." A surgeon has to make an incision to create greater overall health in their patient. Our words, when carrying truth with love, can bring about healing and growth in our friends. Solomon once wrote, "the wounds from a friend can be trusted."
I can remember the times when a friend had the courage to give me feedback that they meant to be helpful. I had the choice to take offense or take heed to what they said. That was on me. But I didn't doubt for a moment, when they delivered that feedback, that they were doing so because they loved me and wanted me to succeed and grow.
The Bible never tells us to to be nice. Jesus didn't die because he was nice. He doesn't strike me as a guy that was afraid to speak his mind, but he also doesn't strike me as someone who was outright mean. It seems like he loved us more than we love ourselves, more than we deserved, because he saw the possibilities of what we could be. He loved the rich young ruler enough to tell him that he was addicted to his wealth and blind to the needs of the people around him. The rich young ruler couldn't receive it, but it's clear that Jesus loved the guy. (because it explicitly says it)
Kindness is one of the key virtues of the Christian faith. In regards to how we speak to others, it is one thing to be kind (speaking the truth with love.) It is a whole other thing to be nice (withholding the truth because you think that is the loving thing to do.) Are you kind or nice?