As for Google, they have gone past their prime. As the other comments note, 2008 was the peak. Yahoo is in the midst of what may be the longest running identity crisis ever to hit a company. And the name of the game for both Google and Bing is to keep you on their site with their advertisements for as long as they possibly can. Like some tentacled monster, they don't want to just serve you and let you go. The cheap tricks masquerading as a flashy UI ruin the user experience and make me not want to go back. Duck Duck Go actually keeps you coming by serving salient information (aka 'value') and then lets you get on with life. Kinda reminds me of the difference between the personality ethic and the character ethic from Covey's 7HHEP.
This was a great post. Thanks for putting it forward.