My take is that the Bloc Party show was good without many people dancing and being into it, but it would've been great if the crowd as a whole, at least the bit at the front was really moving about for it. Not necessarily dancing, but more of a moving of arms and heads. There was a girl close to me at the barrier who had come all the way from Montreal to come to this concert. She was rocking out a good bit, and as I was doing the same, she and I had a couple of moments where we would glance at each other and smile as if to say..."hey this is really great". When the entire crowd up at the front is like that, it lends a great sense of community about the whole thing. It's not just you enjoying the show anymore, you're part of something more.
I must stress however that what i just described is the polar opposite of the moshing/pit phenomenon, which I see as the epitome of not paying any attention at all to the band.