Take a look at this list of potential things you can ask for as a developer:

https://developers.google.com/identity/protocols/googlescope...

And most folks will click "Approve" without really reviewing the list. That said, Twitter and Facebook (two other popular OAuth providers) heavily restrict certain "full" access to only trusted applications that they either have a business relationship with or otherwise review the application before allowing those scopes to be requested or used. This incident may prompt Google to do more of that, which isn't entirely great news for the more responsible developers with purpose-built apps.