The ever-present notion of terrorism is great for business, for government, and as an excuse for prying.
Terrific for business
"Terrorism" is good for the media and for government and other interests who increasingly want to manipulate and control society. The threat of terror provides a common focus and a perfect excuse for intrusions into privacy and freedom in the name of "public safety", which an open society would otherwise not stand for.
Today there is talk of Labour stepping in to fill the gap left when the Lib Dems refused to support the Tories in implementing a new communications snooping bill which would allow the overt monitoring of every UK citizen's internet use. They want to know every person you comunicate with, when, and how. With modern smartphone technology that is effectively every single citizen under surveillance all of the time. Without ever reading a single word you write, they would still be able to infer who you associate with and your movement patterns every day of your life. And it would be on permanent record. The Lib Dems told the Tories where to get off, with this clearly draconian police-state law. But, like the Tories, Labour have always been in favour of snooping and control (socialism and big business have many of the same vested interests when it comes to keeping tabs on the masses), and have offered support. And, of course, those in favour are citing the incident in Woolwich as their justification.
It is already rapidly becoming clear that there was already plenty of evidence that the culprits had come to the notice of the security services, and that they have all the tools they need (including communications taps under warrant) to perform the job. Would communications monitoring have helped? Probably not. But to the uncritical herd the mere idea is justification enough.
Someone, somewhere, dropped the ball. Or did they? Now I don't want to come across as a rampaging loony conspiracy theorist, and I am not suggesting that this is the case, but consider for a moment - you are having difficulty getting your surveillance law passed. Wouldn't it be a fortunate disaster if some small pocket of loons somewhere should fall through the cracks to commit some small, but high profile, attrocity just to catch the public eye again? It's a shame some innocent serviceman has to cop it, but then that's what they do in the field.
You have to ask yourself, which is the greater likelihood? Conspiracy, or carelessness? Carelessness is the more common human failing, but you can't help but wonder occasionally.