I actually think PG is exploring something that is at the heart of what it means to be a human being.

Interestingly, the traditional teaching of Original Sin is that we are broken at the level of what we 'want'. The phrase commonly used is 'disordered desire'.

The key idea here is that if you want the wrong things, you are not actually free, even if you perceive yourself as choosing freely. As a corollary, the more you practice the good, the more you desire it, and the freer you become.