I think it is a mistake to dismiss them as 'particularly mad', by which I assume you mean 'crazy'. Even crazy people have they're own logic and it's usually pretty sane. In this case, I feel like they know exactly what they're doing: They want us to go back into Iraq and are baiting us in the most obnoxious way possible, figuring that if they do something shocking enough, our hand will be forced. And sure, we can bomb them. But every dead civilian (or 'civilian'; it hardly matters) will be used as recruitment propaganda. By weakening them we will make them stronger. And we will ultimately be weaker. They surely know this. That's why they're so desperate for us to rush in.
And here's the thing... they in all likelihood do not care if they die. I do not know their specific tenets or ideology, but I think it's fair to assume that there will be suicide bombings. There's certainly no reason for there not to use suicide bombings. From their perspective, there's no downside. They're fighting the good fight for Allah. So what if some innocent Muslims die. An early ticket to paradise is no punishment. They're like the kamikaze pilots of old, except they can look like bystanders, and boy will there be outrage if a bystander is killed by mistake.
I don't know what the answer is, but I can't shake the feeling that we're about to play their game again, a game that we cannot win.
I would just like to point out that you took exception to me calling them 'particularly mad' and went on to say they would certainly opt for suicide bombers as a main point of strategy. Not necessarily saying that contradiction isn't reasonable enough when dealing with the particularly mad...
As to the meat of your comment, you are I think correct in their general idea that a land war on their turf is somehow 'winnable', when really all it is is a quagmire for all concerned including them. The thing is I really do think we (excluding certain particularly mad neo-cons like Dick Cheney and his crew) have learned the necessary lessons.
1) We don't really seem to be playing the 'hearts and minds' game any more. If some stray bombs hit some non-ISIS...well whatever they were they probably hate us anyway, or would sooner rather than later. We'll bomb ISIS so they don't accumulate too much hardware. We'll bomb a path through them for huge groups of unarmed folks so there isn't a massive loss of life all at one time...and we'll drone strike anyone, anywhere, who presents a genuine threat.
2) If the next group that looks like they might develop a significant power base starts chanting about hating us, we'll bomb them too, even if they set up a voting booth on every corner and say they elected the guy leading the chant. Democratization is out, friendly is in...if that takes an oppressive despot willing to kill off his own people when they insist on 'death to the west', so be it.
3) We don't care so much about recruitment any more. There are enough home grown lunatics in the US that terrorism is just a way of life. A few more trying to swim the Atlantic is just not so big a deal. Every round of 'bomb down the growing top dogs because they are unsatisfactory' reduces the overall capability of the region to produce effective terrorists, because if they go enough rounds they are going to be fighting with rocks and sticks before they fall to someone acceptable.
Let us not forget that we had very little 'terrorist problem' back in the day when Saddam Hussein was our friend, and we were his best friend. In fact for the most part the entire developed world thought the whole middle east was pretty much fine and dandy. Slowly but surely we are headed back there.