People have never acted with common sense, and there was no Golden Age. Whether people will eventually develop common sense, and move in to a Golden Age is debatable. Personally, I doubt such a thing will happen unless certain somewhat technological advancements are made (and honestly, as with all tech, who knows what new problems they'll create).
As for the threat of terrorism, I have two answers.
If we are referring to Islamic extremist terrorism, the only way that it will truly be cut down to a near negligible level (no form of extremism is ever truly eliminated), is if the moderate Muslim population rejects the extremists in a more active fashion. Right now, many moderate Muslims talk about how they disapprove, acting passively. Leaders within the community need to take a more active stance in separating the extremists from the general community.
If we are referring to terrorism in general, it will never be eliminated. People will always have differing views, and there will always be those who try to force their views upon others with violence and intimidation. The most we can do is try to find out about attacks before they occur, and prevent them.
Originally Posted by Working Class Hero
Exactly, we should never try to fix or prevent things because it's impossible to be perfect.
Trust me, we do try to minimalize civilian casualties, often to a degree that puts us at more risk. It just hurts sometimes that people get so angry whenever a tragic accident occurs, seeing it as evidence of our 'evil', when we could be saving hundreds of millions of dollars by using slightly less fancy weapons that would achieve our objectives just as well, albeit with more civilian casualties. We are investing huge amounts of money and personal risk to avoid this sort of thing. There's a reason that the number of civilian deaths in the entire Iraq war (including civilian-on-civilian crime, which is quite common, and those killed by our enemies) is only about double the amount of civilians killed in a single 8-day bombing mission in WWII.
Improvements are being made, it's just irritating and a bit upsetting that so many people think we can just press a magic "make it better" button and eliminate the problem.