It's easy. Right now it's Iraq, Libya, Afghanistan and a few others engaging in war. Decades and centuries past it was 3/4 of the world doing it.
Also, the amount of carnage is much smaller now, despite the technological potential to inflict great carnage being much higher.
Yes and Chomsky himself points out how much more civilized we are now than in the past. As bad as the Iraq War was, it completely pales in comparison to Vietnam, 30 years prior. It's also the only war in history that received protests BEFORE it started. It was also much more brutal than Iraq.
Obviously aggression still exists, but it's more subdued, has to be politically justified more strongly, and receives more scrutiny than before. Again going back to Chomsky, he mentions how in the very early anti-Vietnam war demonstrations, they were only a handful of people and they needed police escort because people were absolutely outraged that they were criticizing US military action and literally were on the verge of getting violent with them.
And I'm pretty sure wars in the early 1900s were more expensive than now. Transportation was obviously much more rudimentary but nations were still willing to ship thousands of soldiers across the oceans.
No, violence still works best. For example, the US would love to have access to Venezuela's oil and sending the Marines there to help the opposition overthrow Maduro would be a cinch. They've done it dozens and dozens of times before.
But our politics and institutions are more civilized now and if they actually did that, the public outrage both internationally and here in the US would be too much so we do it behind closed curtains.