Honestly, IMO, the best value of pre-4e D&D is the rules aren't perfectly balanced, there is a definite need for judgement calls by the DM. To me, that makes a better game.
While NWN and Baldur's Gate were fun, they were emulations of D&D and not truly D&D.
Until such time that AI can handle gray areas and judgement calls, game programs require rules set in stone with no gray areas. So, for now, creating a computer game that is equivalent to D&D is impossible, IMO.
GP