We play a 1 gap defense. A big run stuffing NT would make us better in... you guessed it... only one gap.
1 gap run defense is more about being sound across the whole front seven than needing one big Vince Wilfork type guy.
In fact, the whole league has moved to one-gap systems because it makes pass rushing easier. Even Bill Belichick, who built probably the archetypal 2-gap DL with Richard Seymour - Vince Wilfork - Ty Warren, doesn't run that scheme any more. The guys who run a 3-4 usually use some version of Wade Phillips' offset-NT one gap scheme.