In real life, there are more better defender in the 2 position than in the 1 position. So, I think we need to make this small change, for realism sake.
....yes and no.
I agree, the average SG is a better defender than PG... but it also depends on if you're looking on ball defense vs off ball defense. Guarding shots vs guarding passing lanes vs pressing your opponent off the dribble, or running cuts all over the place to prevent a catch and shoot.
basically... I am saying OD is really simplified here compared to all that.