Only because the expensiveness of obtaining it is offset by how expensive oil is (or will be). That doesn't make it right.
I mean, cannibalism isn't food, but as you run out of food, your fellow passengers seem more and more palatable, right? That doesn't make it right, right? Ever? At the expense of raping the planet, I don't think certain drilling will ever be worthwhile -- we need to start working harder on alternative means of energy, and more efficiently using oil as it is (fuel cell technology, hybrids, etc.).