It really annoys me when I read about anyone implying that Obama 'should be doing more' about the current oil spill, or that he 'is not handling things well'. The oil spill should not be his problem. He should not have to spend any time thinking about it. His time would be much better spent doing some kind of international diplomacy. That, and not some domestic technical issue, is his job description and his comparative advantage.
Katrina was not Bush's fault. The BP spill is not Obama's fault. It is utterly irrational to blame the president of the USA for accidents or natural disasters. It reflects a stupid, primitive, magical-thinking, priest-king mentality that modern science should have driven out centuries ago.
It is true that, in each case, employees of the federal government could have done a better job. But the primary culprits were local governments or private companies. There are things we can do to reform the system to make bad things less likely to happen in the future. But these things have almost nothing to do with the head of state. They are boring details of ethics rules and incentives and should be dealt with via careful thought, not panicked reactions.
It is fundamentally misguided to expect the federal government to protect us from everything. The world is a dangerous and chaotic place, and it always will be. If we ask the government to waste its time on things that it cannot really control, then it will have less time and resources for the things that it can do and that are important.
Anything that Obama does about the spill will be at best a waste of time and at worst actively dangerous. But if he had spent the last month focused on foreign affairs, then he might have been able to prevent some kind of political or terrorist crisis 20 or 30 years from now.