bp does not have unlimited resources. the US brach has 29 billion in cash (publicly traded companies must disclose their balance sheets)
i heard the estimate of 40 billion for the clean up (obviously premature to have any idea)
this tells me they will go bankrupt before they can pay that whole tab. and i am sure their HQ (britan) would rather close the US branch than pay the entire tab.
also they had a blow out preventer. that is all that was required (as i hear it). heck they even had batteries in the blow out preventer (dead ones as i hear it).
i hear there is other hardware that could have been used, but not required and the cost (500,000) is to high... so they would rather take their chances... i doubt they feel the same way now.