Now to your point.

"We will never simply want the things we should."

Is totally correct. I think it is because we and society are not simple. It is and we are complicated. We often want the things we should. Sometimes we might want things we shouldn't. Intelligence can help us understand the difference. Wanting is not evil but doing can be. Society fills our heads with various wants and many can't cope with the sorting of these wants in the should and should not. We are all likely to do some things we should not. That does not make us evil, it makes us human. We all can and must work to make better choices.

TEK