I did my part during both shows I attended, but James could really communicate it better with the crowd. It is not that the fans aren't prepared to do so or that they aren't enjoying the show, it is that it is awkward for people to start clapping in a theater where they are so exposed and they need a little extra motivation.
At the two shows I saw, James said a few things like "sing along" or "c'mon!" but even for me, who knows and loves the album, I wasn't sure what to sing or what to do at certain points. If James makes a convincing overhead clapping movement, that should be clear. We all love the band and many people will have/have had a fantastic time at the show, I am sure many will follow suit in clapping
I do, however, hope fans spread the word to keep standing at the end. I found all people sitting out the final track to be a bit awkward at the first show I saw.