That's a fair point. Still, terrorism was nowhere near as much on the radar then as it is now.

I think it was, it was just a lot more "diverse" on the radar. Terrorism wasn't (and really shouldn't be) considered "one thing", but a spectrum from hijackers to bombers to arsonists, from nationalists to separatists to religious extremists. When people in the 70s/80s used to speak of terrorism there were often more adjectives and synonyms involved.

Jingoism has a hard time with nuance and diversity, so the "War on Terror" (sigh) mentality that terrorists are some how a coordinated force, and "mostly" religious extremists, and who cares what methods they use to promote terror just lump it all together.

Which is to say in metaphor terms, I don't think the number of terrorism "bogeys" on the radar changed, so much as the "friend or foe" system just started using the same color and tag for all of them, instead of somewhat more individual labels. It looks like "more on the radar" because it's easier to spot clusters, but they were there before.