There’s no possibility of understanding the grace of Romans 6 and the glory of Romans 8 unless you identify with the excruciating struggle of Romans 7.
The world we inhabit is wrong in so many ways, and a holistic approach to this “wrongness” traces its cause both to sin itself and to the effects of sin.
There are plenty of reasons why you do not already do whatever you want out of fear of the law, and you will find these reasons persist and remain long after the gospel has its way with you.