Personally I would be a fan of giving users more "knobs" to turn in their search results. For example, we have the toggle switch to include personal results and

Personally I would be a fan of giving users more "knobs" to turn in their search results. For example, we have the toggle switch to include personal results and personalized ranking, vs. showing un-personalized search results. However, it's a complicated product design problem whenever you want to add complexity to something used by a billion people. Remember that the thing that made Google so popular and iconic originally was the plain search box.