Ok now that I've calmed down abit, reasonably whilst I know this pretty much screws up the naruto sasuke dynamic, it is somewhat reasonable. I mean you could see Itachi's final words affecting sasuke and it would make sense given that itachi was everything to sasuke. Coupled with what the 1st told him it is not entirely impossible that sasuke wouldn't 'see the light'. Having said that i wouldnt be surprised if what he's doing now is saving the village so that he can be the one to mess it up personally.
As for orochimaru, until kishi says what was his true motive of attacking the village in the 1st place, i would say he never was a conventional villian since his main goal in life was to learn all that he could about everything which on its own is not inherently wrong, just that his methods were wrong.