They were very clear when they introduced ads based on your email that only a machine would read it. But by opening up access to third parties, they can no longer guarantee that. So this betrays their users and the expectations they have encouraged.
It would have been so easy for me to click through a permissions request, as I would have assumed any permissions were pretty weak - use OAUTH to log in, maybe get my gender or age etc.
If you've had cause to use some app that relies on email analysis then maybe you knew about this, but I'm guessing the vast majority of gmail users are like me, and have no idea an app could request the permission to read their email, and thus provide access to employees at third parties.
The fact that this is being downplayed is disappointing, because it's not dissimilar to Facebook's behaviour in allowing third parties to read messages.
I thought Google were different; I was wrong.
Guess that switch to iCloud mail I was thinking about is now a priority.