I want to set the record strait with this.

Jonathan Kent didn't want Clark saving him not because he didn't want him to reveal his powers, but because he needed to learn how it felt to be a powerless human being. If Clark solved all his problems using his superpowers, it would only distance himself from the world and eventually he could become detached from it.

By forcing him to wait and watch him die, he is basically teaching him how to be human, and how human life is fragile, so that when he finally becomes superman he would be less likely to develope a god complex because he could relate to people.

Used to hate this scene like no other, but it makes sense in the context of the movie, two fathers who develope Clark's identity. One for Kryptonian, the other for Human.