Curtis White in an article entitled Kid Adorno in Context No 6. examines Radiohead from the perspective of Horkheimer and Adorno's Dialectic of Enlightenment. This promises to be more insightful than my initial attempts to make sense of Radiohead White says:

Radiohead's political bete noire is what Adorno called "instrumental rationality." A techno-totalized world. Its artistic quandary is not how to prosper within this totalized context (as their well-wisher Nick Hornby encourages) but how to respond to it in a way that is adequate to what the artist wants: the feel of the authentic, the spontaneity of autonomy, even a tiny gap between itself and the universal other, the Corporate Life World.

It's difficult music for sure.

White then says the following about Radiohead's Kid A:

Call it a self-indulgent refusal of their job description (why, "there's no room for anything approaching conventional pop music," Hornby whines), but this is the obligation or the duty, if you will, that art itself feels it owes to the social. It's as if art's primary function is simply to remind us that there is a difference between freedom and repression, that change is real and the possible is possible.

What really bugs critics like Nick Hornby is that as Radiohead's albums have progressed, this strategy has been taken up less through an explicit "message" in the lyrics while the music remains more-or-less standard pop rock (even if very good pop-rock) and gets taken up more integrally in the textures of the music itself. This is what sends Kid A "beyond the pale." In fact, I would argue that Radiohead's intuition that its politics are best made not explicitly in their lyrics but integrally with the music is a very good indication of the artistic and political health of the band.