What far too many people seem to forget (or they never knew in the first place) is that variation is key to the survival of living things. From an evolutionary perspective, genetic diversity is necessary for the survival of species. If there is too much similarity or too little variation, species have very little to draw upon for adaptation. In fact, we know what happens when too much in-breeding occurs among animals we raise and among human beings. We need genetic variation just to stay reasonably healthy, not to mention adapt to changing circumstances.
In sociocultural contexts, the same idea applies. Variation and diversity is healthy. New and different ideas can breathe life into situations that can become quite stale or stuck. Creativity and problem solving need variation. Democracies need diversity. Businesses and institutions of all kinds need diversity.
We need diversity and variation in people and ideas, because they help us grow. They help us expand our horizons, our understandings, and our appreciations. They help us develop empathy and compassion. They help us develop wisdom.