Yes, though more broadly my point was that the radius is the natural measurement of the circle for most things since most things are center-based. But for some physical measurements, mostly based around pipes, "what is the width of this pipe" is the question you need answering, and that is diameter-based. And pi is circumference/diameter, while tau is circumference/radius.

But yes, if the world switched to tau then you wouldn't need pi anymore, you'd just write tau/2 in the rare cases where having the circumference/diameter ratio handy is useful.