The most compelling argument is the importance of large-scale corporate surveillance to infringements on civil rights. To its (partial) credit, Google is as open as it can be about governmental requests for its vast troves of information. It turns over data to governments more than 200,000 times per year [0], often without a warrant (or equivalent) and frequently to countries with appaling human rights records. Further, it has at least once turned over a list of all people who were in area at the time of a crime [1]. Google may have collected location data for benign reasons, but it has now been used to harm its users. I fear this pattern is going to play out with more frequency and greater severity.
[0] https://transparencyreport.google.com/ [1] http://www.newsobserver.com/news/local/counties/wake-county/...