That's strange, though, because it should be clear to them that the long term effect of this is pretty dangerous for them - if their search results were always the best, then they would be largely unassailable in the search market, but as it is, they're decreasing satisfaction with their product. It's hard to improve everyone's perception of your product once that's happened, and it opens them up to usurpers.

It does, but Microsoft's thrown loads of money at the problem and not made huge inroads so maybe they figure it's worth the risk?

Yes, but that would be pretty evil of them, don't you think? ;)