The Aussie band were planning a comeback album when drummer Prestwich passed away after surgery to remove a brain tumour in 2011.
Barnes told The Daily Telegraph: "How do you find something good out of a friend of 40 years dying?
"I think the best thing we could take from it was that it took Steve's death to realise we're not here for a long time, we're here for a good time. Let's enjoy each other's playing, let's do it as much as we can."
> Cold Chisel to release first new album in 14 years
Bandmate Don Walker also said of their reunion Light the Nitro tour last year: "That was a dream tour, as far as coming out the end of it with everybody even happier and more relaxed than going into it. And I think the people out front could tell that. In Cold Chisel's history, that is unprecedented."
Ian Moss said that the "roar" of the crowd when they played in Cairns was "inspiring", with Walker adding: "I was taken aback. We couldn't hear ourselves."
Barnes also said that he gets upset with the music scene sometimes, saying: "In this day and age, people just wanna be famous, they don't care if it's for being fools or being abused. It's not about talent or anything.
"I get invited to do these celebrity shows all the time; you've got the wrong bloody fella here. I'm a singer. I'm not a celebrity.
"It's the modern culture, instant communication, everyone wants [their] 30 seconds of fame or whatever it is at any cost - and it doesn't matter if they have to lose their dignity to do it, they do it. It's just wrong, you know."
> Cold Chisel prepare for record-breaking release
Watch Cold Chisel perform 'Khe Sanh' live below: