Diversity of ideas is a strenght: you need one or two people who look at things from a different angle than the rest of you. Cultures sharing food and recipes, exchanges of agricultural practices to suit different climates and adapt to new ones, legal experts who work different jurisdictions coming together to understand unique law cases, old people sharing wisdom and young people teaching technology, parents sharing how to parent better, rigid thinkers and flexible thinkers tamed together - all these things are good. These can come from different living circumstances, which can be geographical, economical, and cultural, and a group of all one race people from lots of different backgrounds is still a diverse thinking group.