We figured there wasn't much reason to restrict what we ask for. I'd like to verify that with data and run a test.
Everything we asked for has a hypothetical future purpose or a present value as an implicit user survey. We could, for example, make the photos upload experience to facebook much better. That requires posting photos and also reading photos to understand how much our users might care about the feature.
We could just ask for that access later, but this is easier. Users are getting something in exchange, so for most I'd bet it is a fair trade: capacity boost for data.