You seem to be implying that its a negative that one of the Assassin specs relies on sneak attacks despite the fact that the Inquisitor thrives on being a cunning SOB. My point is that the Inquisitor may be a force prodigy, but that does not mean that they'd be instantly torn to pieces if the Warrior got up in their face with a lightsaber.
I'm implying that toe to toe, the most lightsaber-using Sin spec can't stand against a Warrior. Speed, power, mastery of Control (as in Force discipline, not CC) - there is no contest really.
If you tank a Marauder with a non-Darkness-specced Sin without using Deflection, Low Slash, etc. then you *will* get torn to shreds almost-instantly. But if you drop on him, and use the CC you're given, you'll very likely come out on top.
That's the thing - Inquisitor wins by cunning and surprise in this case. The Warrior wins by discipline and skill.
Darkness is another matter - but high-level Darkness Sins rely on the Force more than their lightsaber for both, attack and defense.