Colour correction is a huge part of the editing process as it can change the lighting of a scene to suit your needs as standard footage without colour correction might not be visually appealing to the audience. It's a small thing that can make a huge difference in presenting the film as it gets rid of any flares or contrasts and can make scenes more or less darker to show a certain mood or atmosphere.
You can see the difference in the video below:
PS: The colour corrected version is the one on the left, the non-colour corrected version is on the right.