Deja Vu
The Harrier, or rather P1127, started off barely able to hover on tethers ( rather hairiliy, and I still know the people in those films, was honoured to work with them decades later );
From a stripped out barely hovering machine, it wasn't long before the thrust increased to be useful, transition flights were undertaken, then hey presto the 2-seater emerged.
Some would say 2-seat trainers should be available from the word go, but life & engine development doesn't work that way...
I'm sure as soon as the F-35B or whatever model is ready, a two-seater must be high on the list; if for not for training, for taking high ranking U.S and other customer types for a ride, which is crucially important - I'm not joking !