Google's motives tend to be just having as much data as possible so they can draw powerful inferences from it, in contrast to Facebook which mainly values exclusivity over their data. By playing the "good guy" card, Google:

- Generally encourages more data to be out there and available

- Pressures companies like Facebook to play along, weakening their data strongholds, lest they be painted as the bad guys

- Gets a lot of goodwill and, more importantly, user trust, which encourages people to give them even more data

While Google's interests seem to align with consumer interests more often than those of the other tech oligarchs, they don't do anything out of sheer good will.