I think the album is more than just about being about the dangers of consumerism, although that's definitely a part of it. It's more a wider warning about consumerism, technology, the corporate culture - maybe about what society itself is heading towards. As I said, I think "Fitter Happier" sums up the album.
I don't necessarily think that every warning, or concern has to be 'angry' as such. I like The Clash and The Jam and to some extent the GoF but they definitely share a similar style - punky, guitar based music. There no problem with that, but Radiohead aren't a punk band. I'd probably mark them down more as progressive if anything. People can be angry, and express that anger, in different ways. I'd say that What's Goin On is a perfect example of this - it's absolutely beautiful, but is also 'angry' at what is happening. I can listen to that album, and Ok Computer, and feel uplifted by the musicianship but also listen to that deeper message.
I don't buy the idea that Thom Yorke does music for money or is at all bothered about how much he makes from it. I'd regard him as an artist the same way that Paul Weller is. They would do this even if they worked in a factory.. The journey from Pablo Honey, The Bends, Ok Computer, In Rainbows and Kid A shows that they move on. If you liked Ok Computer, then In Rainbows is a 'hard listen' I think. In fact it's nothing like their other albums and again, I can't think of any other mainstream artist they sound like. He could easily have pumped out Ok Computer 2 and raked it in, but they moved on as musicians because they are artists and feel they have something to say.
I love Creep too :) maybe you had to be there, but I remember hearing it for the first time in the early 90s in "The Shack" in Oldham and you'd not heard anything like it. We all just kind of stopped and listened. It was this lovey-dovey song then that guitar crashes in with the "you're so f**kin special" line and it just sounded incredible. I wasn't the only one who thought that.