Or maybe they understand (correctly) that for general air combat a massive advantage in roll rate is more important than a much smaller turning advantage. Clipping those wings for high speed roll gets rid of the only handling frustration to be found with Spits in-game.
All true, until the fight gets slow. That's where the full span of the Mk.VIII makes a big difference. Also, there are various ways to counter a superior rate of roll. Maneuvering on a different plane than the faster roller can often offset the advantage. Against the Spit16, you don't attempt to follow. You go out of plane and cut the corner. Having fought many duels against the better Spitfire drivers, I find that the Mk.VIII is superior below 200 mph. At high angles of attack, the Spit16 is more prone to snap-rolls. Of course, unlike dueling, the MA environment varies greatly.