I have to think that ad revenue is the prime metric, and Google is loath to change search non trivially to improve UX according to the measures you list. Read

I have to think that ad revenue is the prime metric, and Google is loath to change search non trivially to improve UX according to the measures you list. Read the emails released in the recent antitrust suit and you'll see intense pressure not to make changes to search, or even to Chrome flows that drive users to Google search results. Bottom line, if ads is performing, what incentive is there to change?