ColourOfSpring - 7:10 am on Apr 16, 2013 (gmt 0)
To lower or just maintain their market share % Google can either lose visitors (and ad click revenue) as a percentage of searchers or people have to find the answer they're looking for with less queries on Google, meaning Google's results must get better, not worse, for them to lower or not grow market share and maintain profitability.
What they need to do to keep from having too much market share while retaining profitability is the exact opposite of what you are suggesting they're doing. The worse their results, the more queries people have to make to find what they're looking for and the more queries people make on average the higher their market share becomes.
Just recently desktop searches hit an all-time high in the US ([searchengineland.com ]). Make of that what you will. In any case, the search share has been pretty stable with Google holding at around 70% in the US regardless of volume. It's hardly made huge leaps in either direction for years in other countries either. The feeling I get (and it's just a feeling) is that Google are pretty happy at this kind of market share in regards to being accused of being a monopoly. It's high enough that they still get continuous flak from the EU, but it's not TOO high to seriously put them under pressure.
In regards to gaining market share through more searches per user - I think if a searcher got frustrated with Google's results and did more searches, he or she would eventually just quit and go to another search engine. Simple as that. Of course Google do not want that to happen. That's NOT a way to sustainably gain market share - but it's a great way to lose it.
Google want to be the best and remain the best. That doesn't mean that "good enough" is the lowest standard possible that keeps them no.1 - when I say "good enough", I mean Google find an accuracy level that keeps searchers happy, and maximises their profits. That's just good business. Your view is that Google will maximise organic accuracy regardless of the impact that will have on Adwords. You might be right (and we're all guessing here), but I would be very surprised if you were.
Just a visual example here. Compare SERPs in 2005 to today on a commercial search - more ad space, less organic - quite often organic is below the fold on common screen resolutions. It's just a visual representation of what ad clicks mean to Google. They will work right up to the threshold when it comes to maximising ad clicks - the threshold being searcher satisfaction. They don't want to breach that threshold (that would be stupid), but clearly they want to maximise ad clicks by working right up to that threshold.