No, IED's was just a convenient example (specifically, a convenient example of a manner of exerting psychological pressure. Given that 30+ IEDs are detonated a day, but kill relatively few people, and VERY few Americans at this point, it's an ineffective manner of producing casualties. It's a very effective psychological stressor, though, as no one in a convoy ever knows where the next one's going to be.) The same thing could be said about sporadic sniper fire, or random rocket attacks on northern Israel, or the opening "shock and awe" bombing in the invasion of Iraq (though it's tough to conclusively define that as "terrorism"...but I could make a good case for it).
But I was trying to make a specific point about psychological effects with my IED example as an example. I wasn't judging IEDs themselves, or failing to judge any other device, so don't read too much into it.
Plus, if you're focusing on technology, you're probably missing the point. Terrorism isn't about the material used.