[fpgeek]

I don't think it's about the market value of Google search in isolation (which is large and positive). Instead, it's about two things:

1. The power of browser defaults puts browser vendors in a strong position to demand a cut from third parties that make money from being a default.

2. Yahoo and Bing (plus some regional options) are realistic alternative bidders for this preferred placement. That dramatically tilts the bargaining power towards the browser vendor. With an alternative, however, a browser vendor still makes some money if negotiations with Google break down. Beyond that, a realistic alternative means Google loses more. Assuming negotiations broke down, more users would end up searching at Google if there were no search engine default than would if there were an alternative one.

To build on the cable analogy, suppose sports leagues were required by law to license their broadcasts (with the same terms) to any cable channel that wanted them. In that case, it wouldn't be hard for someone to put together ZSPN and bid away ESPN's carriage fees. ESPN doesn't just get those fees because they have valuable content - they can demand those fees because they have control over that content.