The reason it isn't destroying habitats nor wiping out ocean life is that those oil seeps are just that: seeps. They are seeping out in literally millions of little locations throughout the gulf and very slow periods of time. The volumes and the time periods in which these leaks are taking place are small enough and slow enough that nature can handle it, somewhat (however, it is a fact that oil is in fact poison to most life forms, except some forms of bacteria, so life isn't actually thriving around those natural leaks, either).
This, however, is not a slight seepage. This is a gusher. This poses a couple of problems.
One is that nature really can only handle so much of this natural seepage. Nature does not adapt quickly to large problem such as this - so suddenly being flooded with roughly twice the amount it is normally introduced to, this does become an emergency situation. And, again, this is in a very focused area, not in the entire gulf. A tremendous focus like this can only do great harm to the environment, and is not something which nature can simply shrug off.
How much business has the shrimping industry lost to natural seepage? How come we don't see pictures of oil-covered beaches and wildlife all the time from this natural seepage? How come we don't see shrimpers and tug boats attempting to skim the surface of the gulf from this natural seepage? Hell, if it is so common, we shouldn't have to drill at all - we should be able to skim over the surface of the gulf and get plenty of black gold.
Then there is this: Legally, food manufacturers are allowed to have a very small percentage of rat and insect parts and shit in the goods. A VERY small amount, but an amount nonetheless. However, if we took all of the shit and parts that you literally consume every year, piled it in front of you and told you "All you have to do is eat 10 percent", could you?
Probably not. As you eat the hot dog, you are not tasting the little cockroach legs or rat shit - you are going to taste the processed meat. That is because, again, you are eating a very, very, very small percentage of cockroach leg and rat shit in one sitting. In other words, those legs and that shit is very slowly seeping into your system - and your system is able to handle it, somewhat. Just as nature is able to naturally handle the seepage which is introduced into it each year.
However, were you to eat all of that shit and those legs in one sitting, you would most likely become very, very sick. Your body is not equipped to handle such a large spill of fecal matter and insect parts - as nature in the Gulf is not equipped to handle such a large spill of oil at once (hey, pretty good chance a lot of that oil IS ancient shit and insect parts as it is!).
This is why we are seeing the disastrous environmental effects of the oil spill.
