I think in terms of things commonly measured on Earth we don't benefit much from the jump to megametres. The diameter of this planet is 12,742 km. Does it help

I think in terms of things commonly measured on Earth we don't benefit much from the jump to megametres. The diameter of this planet is 12,742 km. Does it help much to say 12.7 megametres? Not really. Off planet the distances between objects are far beyond megametres. AU, parsec, and lightyears make much more sense.