Obama is the man who doesn't WANT to have a plan
Obama isn't cautious about ISIS, he's annoyed. He has stuff he wants to do to the United States, and he was really enjoying the luxurious perks of the Presidency. He wants to stand in front of adoring audiences - he prefers either students, or people who paid tens of thousands of dollars to hear him speak - and spout the same tied old lines he's been using since 2008, to thunderous applause.
He expects a significant return on investment when he sinks political capital into something. When he makes what looks like a sound investment and it doesn't work out, he gets very crabby. Remember how angry he was after his seemingly slam-dunk push for gun control after the Newtown horror blew up in his face? That's what Angry Barack looks like, not the mildly distracted man who dropped off a quick statement on the murder of James Foley, passively hoped that other people would get rid of ISIS for them (or they'd just go away, because they have no place in the 21st century) and was smiling and laughing merrily on the golf course less than half an hour later.
Obama's not going to invest his energy in something that offers him no domestic political gain, no further accumulation of power. He wanted to write Iraq off as a Bush mess he cleaned up. The prospect of going back into battle there and validating Bush frightens and nauseates him. It's a guaranteed political loser domestically, as he'll receive little applause from serious people who remember how Obama stood by and let the Islamic State take root... and he's certainly not going to get any love from the silly people who think global terrorism will go away, if we ignore it.
Fox News reports today that Obama was "given detailed and specific intelligence about the rise of the Islamic state as part of his daily briefing for at least a year before the group seized large swaths of territory over the summer," according to leaks from Pentagon officials, who are tired of Obama blaming them for his blunders. That means Obama had been warned about ISIS before he famously dismissed them as the "junior varsity" league of al-Qaeda. He ignored the warnings because he doesn't care about such threats, and has no idea how to deal with them. He rolled the dice and hoped ISIS would be entirely occupied with fighting the Assad regime in Syria for the remainder of his term in office. He crapped out, and now he's got no idea what to do next, so he's falling back on what he knows best: manipulating U.S. media coverage to keep his Low Information Voter base quiescent.
The Washington Post ran a remarkable editorial this weekend that discussed Obama's "disturbing" performance, essentially complaining that he's lost touch with reality, and spends too much time "explaining what the United States cannot do and cannot afford." That's a striking difference from the way Obama talks when he's got a juicy new domestic power grab in mind - there's nothing government can't do on those occasions, and Uncle Sam's fat bankroll is limitless. Those domestic initiatives are profitable for Obama - they pay off in social engineering, vote-buying, and "historic" legacy achievements. That's the stuff he wants to do. On foreign policy, he's going to double down on his bet that things won't get much worse in Russia, Iraq, Syria, Libya, or the rest of the hot spots if he mostly ignores them. As long as nothing awful happens within the borders of the United States, he thinks he'll win that bet. And if he craps out again... well, there was no Plan A or Plan B, so there sure as hell isn't a Plan C.