ONE tickets are not booked in Q,W,Z classes so you would earn more miles on your trip and thus more free flights.

me and my partners last AONE4 was not mile maximised nor status but we still have earnt enough miles to get 2 x free biz tickets to the US on BA (amex voucher) and a free biz ticket to Asia

i paid $6,000 p/ticket so if i ws to go round the world again (as elite status) i would be earning near to 1 free rtw for every 3 booked, so depends on how you look at it
or in excess of 160k miles per trip which is a free tick in F to US ,
i would assume you would value that at a few thousand dollars

so for every 6k i spend i would value what i gain in points and status lounge access etc etc.. easily worth another 6K,
so the cost (to me) then makes more and more sense.

with planning you can get 20 flights with 60k miles for 5k approx in J, so would you think $250 a flight in J is expensive or cheap?