For me it's neither. It's about not flying in excruciating pain due to the seat back angle. I need a few extra degrees of recline or my lower back is in absolute agony even after a short 1 hour flight. I flew Jet Blue (no recline) once and it was the most painful flight of my life. Never again. If they'd recline the seats by several degrees, all of the seats, then I'd personally have no problem with them removing the adjustable recline. Until that day, I will recline my seat.
By that logic, seats shouldn't recline on short haul flights. Nobody needs to sleep on a <4 hour flight.
I will say sleeping on flight isn't easy. I've flown a lot and have been lucky enough to be in real business class three times (British Airways, Virgin Atlantic, and a budget airline) and I've only slept once ever in all that flying. Virgin Atlantic's completely flat beds got me snoring (the other two airline's "almost flat" chairs did nothing).
