Obviously these attacks in recent times will have made us think more as they are attacking our world of music but from an organisers point we can only do so much and these atrocities have shown that. I believe security are more vigilant at chucking out time rather than just wanting to close the doors but you really just cannot expect something so awful to happen.
I run my own festival. Its quite small (750 footfall over 3 days). We have just 4 security (24 hour) across the weekend. Every bag is checked before people enter the venue but apart from putting in metal detectors (excuse the pun, its a metal event) the only thing we can do is stay alert.
I work for a company that has 12 festivals a year with 6,000+ people at most of them. They are held at a holiday park (we rent the whole park with the caravans and chalets etc). The security there is very tight. They have barriers before you get near the 2 arenas and lots of security who pat you down and check your pockets and bags. They have done this for the last 11 years though and I have never felt more save than when at these events but if someone was determined to maim and kill then they will always find a way.
I got to a lot of football matches. 50,000 people inside a stadium and I have questioned for years how easy it would be to bring a weapon into the venue. Security is very lapse at most football grounds. I have travelled to 65 of the stadiums in the country and its such an easy target. I am surprised attacks haven't happened.
I think majority of people will be of the mindset that they will not be stopped doing what they enjoy and will be defiant against any attacks in their own communities. The music scene, especially the rock and metal where I am, is one of a very strong family. I see the same people at 10 different festivals a year. They have become friends away from home. Not one or two people but hundreds of the same faces. They will not let this deter them.
After the Manchester attack was my own festival the same week. There was a planned minute silence at all music venues around the country at 10pm which just happened to be when a band from Manchester was on stage. The emotion in the room was so strong. A lot of bearded men cried a few tears but as we all linked hands, all 500 of us, we felt a strong bond and that we would not be beat by hate, terrorism or anything else thrown at us.
So in short (well long)... we will carry on regardless because you can get on a tube train, you can be on a plane, a bus, walking down the street, in a place of worship and still an attack could happen to you.