The question of what to do about Google's dominance in search, and do we care as a policy matter, is the confrontation between whether we care about actor motivations or actual impacts in policy land. Lets take a simple example: Google's decision to include Google Maps as part of a returned search result for a geographic location has had a profound impact on the traffic to other map sites, threatening their viability. That's a reality. But Google hasn't done anything wrong under traditional antitrust policy. To the contrary, they argue with some justification that their users (a) really appreciate the feature, and (b) that there is almost no switching cost or barrier to a user simply pulling up Mapquest if that user prefers. Heck, anyone can go out and devise an ap that will allow a motivated user to seamlessly take a Google search result and plug it into Mapquest. Unlike MS, which took active steps to block competing aps, Google doesn't -- at least for now. After all, Google has no responsibility to send customers to Mapquest.
Which is true. But the reality is that behavioral economics is right and reality matters. People do stuff in predictable ways despite the fact that they could do something else. But unlike previous natural monopolies, the information monopolies rest much more on maleable aspects of human behavior.
Put another way, Google is capable of creating delicious bread crumbs to lead me through the woods to the magic candy house where it can serve me for dinner in a dozen different ways, all the while training me to be like the cow from the Restaurant at the End of the Universe delighted to offer up my various organs and muscle tissue. Indeed, the more I use Google, the more it knows precisely what breadcrumbs I will find irresistible, and the more it trains me to offer up various bits of myself for consumption. This troubles me. OTOH, these are really delicious bread crumbs, with just the right amount of garlic and Parmesan cheese and a hint of something I just can't place but is really yummy. Ooooohhhhh!!!! A gingerbread house . . . I wonder if they need my liver. It should be tender now.