Recent news (http://www.omgubuntu.co.uk/2012/09/online-shopping-features-arrive-in-ubuntu-12-10) indicates that the home lens will, by default, search Amazon for products to put in the 'More suggestions' section. This means that regular searches for local applications and files are transmitted to a remote server, which I believe breaks an expectation of privacy. It also seems somewhat tasteless for my operating system to be advertising things I might want to buy. Finally, the idea that Ubuntu is now ad-supported has brought considerable negative PR on tech news sites like Slashdot and Hacker News.
All of these problems could be easily avoided if the shopping lens were separate, rather than showing results in the home lens. The shopping results would still be very convenient when the user wanted to see them - they could opt in with a single click, as we currently can with the video lens, for example.
To anticipate one likely response: I understand that this feature can be removed by uninstalling the package. I believe it should be opt-in, not opt-out, and I also think the feature is useful, so I don't want to remove it completely from my system.