[mikewhy]

This also works in TypeScript's favor. Meaning you can skip writing tests that simply check you're giving the correct props.

[nailer]

I don't think anyone /does/ write tests that simply check they're giving the correct props. They write unit tests, and props are part of that.

[eyelidlessness]

This also works in TypeScript's favor. You get test coverage which you would never write. A "simple" component that doesn't have any logic and doesn't warrant a test still checks its prop types, and you don't have to do anything other than make the compiler pass.