Ever since the Cold War ended the quality of terrorism is in decline. With no superpower to arm and train them (against the other super power and its client states) their methods have become cruder and the quality of men have degraded.
Terrorists face a double-edged dilemma: to be effective they need organization and various talents. However the more organized they get, the higher the chances of being discovered and infiltrated.
All in all I wouldn't say that terrorism has become more sophisticated or effective over the last 20 years - in the places where it happens more it is usually highly overlapped with defensive guerrilla warfare - whereas we see less and less effective international offensive efforts like 9/11.
...the main problem though is that the western world is hooked on fear and the media plays it up to eleven. Our leaders also exploit the situation the grab ever more power under the pretext of security. Terrorism has also become a buzzword and an easy reason to deal harshly and dumbly with complicated situations. It was never well defined to begin with and one man's freedom fighter is another's bloody terrorist:
...so your picture about what is terrorism, what is actually effective against it is likely really opaque and fuzzy. In the place of concise judgment and honest measures we have a massive security theater that's meant to convince us that those in power are doing *something* and to make us *feel* secure (but actually do little to make us more secure than we would be in the first place).
The greatest problem with this theater is that
we're achieving the objective of the terrorist for them instead combating it.