Ooh, ooh! I have an idea!
Because in the original, they where copying Aoki-sama's style, like they usually do in animes. But then they decided it would be a better idea to give them a younger and brighter look, to draw in more attention to the show and therefore make more money =3
Or at least.. that's a possibility..
Maybe they earned enough money from the first season to change their art? Gah, goodness knows what they where thinking XP But you've gotta admit, without V-Force style, there'd be no G-Rev..