I think Obama's refusal to comment is not a sign that he is oblivious to the situation. Quite the contrary, I think it has to do with the religion of the pirates. If the Muslim world can elicit a direct response from the POTUS with something as simple as attacking a dingy at sea, then it will encourage more sea-borne terrorism.
Basically... he won't address the pirates because they are too lowly to be given word from such high office. In addition, piracy at sea is not new. It has been an ongoing problem during all of the modern Presidential administrations. The media is just giving it more hype now, which is why more people are expecting a comment from the POTUS.
These situations happen more often than we knew until now, and the navy has always moved in to address the problem.