It was opt-in. The opt-in message wasn't at all clear (even to me, and I'm a top-100 Quora user), and was presented on first use, not in a settings pane, when you first tried to view a view list -- it wasn't really clear that it reciprocally opened your own views to tracking.
The feature itself isn't horrible (followers on questions and topics are already public, and this is well understood and IMO worthwhile -- you CAN follow anon too, but it at least increments the counter), but was badly presented to users. I think just out of incompetence, not malice.
http://www.quora.com/blog/Introducing-Views-on-Quora states "All Quora users participate in Views by default, but you can delete any individual view from the content's views page, or you can turn off Views anytime on your settings page."
What communication? If they had let people opt-in, or even asked them to opt-out then that would have been communicating.