Urchin,
There is another reason. Getting close now really matters if you want to hit. In AH2 the Spitfire and N1K2 both rely on their enemy being slower than them, an unusual circumstance, and then simply cutting their corner whereas in AH1 they could rely on the spray and pray to kill a fasgter egressing aircraft. The La-7 and other fast aircraft enables the pilot to get to close range without relying on the enemy making a mistake and can also easily egress from slower aircraft like the Spitfire and N1K2.
Speed enables killing much more in AH2 than in AH1.