Pirates are the new pirates.
Jeez, haven't you seen everything happening over in african waters with the pirates there? The pirate way of life is still very much alive and kids like Cartman want to grow up to be them.
The problem is there have always been cool stories about particular pirates that kids could idolise. The chances of us liking the stories of misguided fanatics is almost nil. In fact, no one would want to read those stories, as the main character dies at the end.
Pirates weren't just about killing, they were more greedy outlaws like something you might find in the old west in America. Terrorists are nothing like this. Notice that both cowboys and pirates are seen as cool because they step only just outside the law, whereas terrorists just take it 1 bombing too far to be cool.
Their outfits are silly and unwieldy, without a hint of class; their weapons are the ultimate cowards tools, and I show my hypocrasy here as I said I liked explosives in that other thread; their motives are hard to identify with, no loot or plunder except some pipe dream of virgins, kids won't understand what virgins are.
Maybe from the point of view of an islamic/muslim child, they could be pirates, but not for western society.