It’s of course true that oil rigs don’t “generally” cause spills in the sense that on the vast majority of days there is no spill. The problem is that when spills do happen, it’s catastrophic. It’s never been accurate to say that hurricanes Katrina and Rita didn’t lead to drilling-related spills and now we’re seeing today once again that offshore drilling poses a clear and present danger to the surrounding ocean. If that were the only problem with drilling, it would probably be a problem worth living with, but given that there are many reasons to think we should be attempting to transition to a post-oil economy endangering the oceans to simply postpone adjustments that are needed anyway seems shortsighted.
If we actually need the energy, and there are no reliable alternatives, then we should be willing to pay the price of what is often a dirty, dangerous, even disgusting business--extracting and burning the so-called fossil fuels. If offshore drilling is unlikely to produce much energy, the danger to human beings and other living things is extreme, and there are good reasons to switch to other sources of energy, then those arguments should be considered. Damage to the environment, especially if it is short-term, does not determine the whole debate by itself.