There's no question that there are upsides to playing with a click. Why wouldn't you want the band to have something that keeps everyone together? Why wouldn't you want something that defines the tempo, so it's not up to how drunk or high the drummer is when he clicks his sticks four times? And of course today's shows have graphics on the screens and other presentation elements that need to be timed to the music, and I don't know, but I would bet money that there are sophisticated multimedia systems that can coordinate all of this, all synched to the click, marketed to touring bands and others. Great stuff.
But the old fogey in me points out that bands were playing together live for thousands of years before there were click tracks. We did this by listening to each other and paying attention to each other. And half the fun of a live performance is that you can do that one section as fast or slow as you want, and we do fuck around with each other, actually challenge each other to keep up, maybe go around one more time with the solos, and none of that is scripted. It has to be in the moment. You can't do that in today's world.
I've been playing live music a long time, longer than most posters here on DTF have been alive, and definitely longer than click tracks have been universal. I suppose that makes me a purist, and purists tend to get a lot of shit about stuff like this. Dream Theater is an absolutely amazing band. To be able to play those songs live, perfectly (or near perfectly) is something I'll never be able to do. But there's a part of me that knows that one reason they can do it is because of the click, and there's a tiny part of me (the purist) that mumbles "Yeah, but that's cheating." I'm not complaining that they use a click, but it adds a homogeneity to everything, it takes just a little bit of the "live" out of the live performance.