The basis of the vow is that intoxicants cloud our minds so that we don't see the true reality which Buddha teaches us about. Also the side-affects of these can lead to our mishaps, and can affect the lives of others.
We can get our minds in so deep into some of these that it really does intoxicate us, altering our minds just like a controlled substance. We are unable to think clearly, see truth, and see things as they really are. Not only that, but the side-affects can hurt others and affect their lives in negative ways as well.
By being mindful of our thoughts and emotions we can better control these impulses, recognize them and deal with them by more skillful means.