I think it’s more that it provides the supernatural gifts (grace) through which we can overcome our basic concupiscence.
You can’t look at original sin as something that destroys your free will. Perfect choice would mean that you would be constantly aligned with the will of God–because that’s what’s best for you. Original sin clouds your judgement, because Adam chose to be like God, and so God became hidden to us and we have to chose Him with our free will.
It’s like taking drugs. It’s a bad thing, I would imagine everyone who gets themselves into a position where they’re about to inject heroine knows that, but their decision making process is clouded and instead of choosing life, the think that the inevitable repercussions will not happen to them, or that the wont become addicted or whatever. Their rationality gets in the way of the divine will–what’s obviously best for you, i.e. not to take drugs. Make any sense?
You can reflect on it in terms of the Divine will of Jesus. Jesus had a human and a Divine will, but would he have any free will if He knew the Father and thus (through the hypostatic union) knew the will of the Father? The answer is the true nature of freedom. The Pope puts it like this:-
Those who understand freedom as the radically arbitrary license to do just what they want and to have their own way are living a lie, for by his very nature man is part of a shared existence and his freedom is shared freedom. His very nature contains direction and norm, and becoming inwardly one with this direction and norm is what freedom is all about. A false autonomy thus leads to slavery: In the meantime history has taught us this all too clearly. ~Pope Benedict XVI; Jesus of Nazareth, (Bloomsbury, London, 2007) p.204.