Let’s take that thought to its conclusion. If clicks on Google really account for only 1/1000th (or some other trivial fraction) of Microsoft’s relevancy, why not just stop using those clicks and reduce the negative coverage and perception of this? And if Microsoft is unwilling to stop incorporating Google’s clicks in Bing’s rankings, doesn’t that argue that Google’s clicks account for much more than 1/1000th of Bing…
What if it slows down innovation in search quality and moves effort into marketing, shiny baubles? After all, why bother spending resources on researching, implementing and evaluating the algorithms when your competitors will within a couple of months gain the most of the improvements, automatically with no effort.
You complain about search relevance sucking. Why are you so eager to support a practice that has a high chance of causing it to stagnate?