I'd say it's far more engineering than creative. You're writing code to meet the specifications of a client. I don't think the race of the person writing that code makes a difference.
>Does the product benefit more from being reviewed by teammates from the same schools and employment backgrounds, or by ones with different life and professional experiences
It benefits from being reviewed by people who have lots of experience writing different types of software. Which has nothing to do with ethnic diversity.
>Besides, getting to know people from different backgrounds and cultures can only expand your own view points and make you a better developer
Meaningless platitude, unless you can back this up with data
>Your point about companies pushing diversity to prevent unions sounds conspiratorial at best.