it probably gets those numbers because Nc3 is highly transitional. What really matters number wise is what the opening ends up becoming after the first few moves.
e3 though, has just always struck me as being too passive and non-commital; but that is just my opinion.


Today I studied openings with official Rybka 4 evaluations. Many surprises for me and it starts already at the very 1st ply:
1.Nc3 has +0.07 as good as English opening and 1.e3 has +0.04 as good as King's Indian attack.