In the case of Google, our RSS subscriptions are such a good signal as to our likes/interests/passions that getting this data into Plus provides great value for both engagement on the network AND for enhanced ad targeting.
@C Batsta – Who said anything about walled gardens? Google allows us to take our data with us (Google Takeout) but integration fits with the goal to streamline the user experience. Use it or don’t, iit’s your choice.
It’s the same with sharing – everything is down to choice, choose to share items from your feeds if you feel the need to do so. Many RSS power-users use it for curation so an integrated solution simplifies the process for Plus users.