To Google, it’s all about better data analytics and business efficiency. First, in place of many separate privacy policies and fine prints (assuming you read them), you have to read one. Second, by linking information about your online movements, interests and preferences - gleaned from Gmail, YouTube, Google search, Maps, Google can synthesize more complete individual profiles and hence serve up more targeted ads and more customized content.
To be fair, the new policy is not about collecting new or more information. But it is about centralizing or merging all your trail from otherwise disconnected Google products. It is about building a more comprehensive profile by linking data crumbs from everywhere - YouTube, Gmail, Blogger, Google TV, Google+ and particularly from the history of surfing based on Goggle.com searches.
Clearly this demonstrates the tension between better integration of consumers’ information (and hence better business value of the data) and underlying un-ease about more organized monitoring of our online behavior. And it raises a good question, e.g., is an immediate in-your-face targeted ad for weight-loss products a value or a violation of your privacy when you’re only making a discrete search for weight-loss solutions and/or listening to a motivational YouTube link on diet management?