> How many of the Firefox users actually wanted Pocket and how many are using it?
Honestly, since when does users (talking about your average Joe) know what do they want? IMHO, I don't see the harm of bundling Pocket if including it improves the experience of users.
The only concern should be the privacy implications.
Apart from the privacy issue, I consider the integration of a proprietary third-party provider to be a concern. I am totally fine with the functionality itself being added, but it should be a Mozilla project. I could see myself becoming a user then.