Why doesn't Google spin-off Reader?

By now Google has a fairly established track record of developing products and killing them. But why wouldn't they ever sell these? Spin them off as independent companies? Or put them up for auction? If the problem is that they are not making enough, why not cash in on all that investment? I can't think of when they've ever done anything like this with one of their services and can only speculate why. But I can imagine lots of companies who would love to inherit a hard-core audience as large as Reader.