I think I would justify it along the same lines as biodiversity is usually defended. With changing external conditions, a niche species may suddenly become of c

I think I would justify it along the same lines as biodiversity is usually defended. With changing external conditions, a niche species may suddenly become of critical importance to an ecosystem. In the same way, humanity faces challenges, and at a certain juncture, a completely different approach to life might make the difference between survival and extinction. But that can only happen if that diversity of approaches has been conserved, and global culture has not become monolithic.