have to say, I cant remember having to adjust a fd really after setup. Maybe a few times but that was usually a sign that cable was fraying inside brifter and I couldnt see it.
and yes, one handed adjustment is easy, but again, very rare the need.
I've had cables fray, slip, and even a FD that slowly slipped a bit on the seatpost once (it seems it was slightly loose from the factory). When that happens, unless it's catastrophic failure or you have a hundred km remaining to get home, it's easier to twist the adjuster a little bit, finish the ride, and solve the problem later.