It's likely in response to Ubuntu's controversial new "feature" of including Amazon search results in unity search (http://www.theregister.co.uk/2012/09/24/ubuntu_amazon_sugges...)
In a subsequent blog post, Mark Shuttleworth says: """ What I offered to do, yesterday, spontaneously, is to invite members of the community in to the things we are working on as personal projects, before we are ready to share them. This would mean that there was even less of Ubuntu that was NOT shaped and polished by folk other than Canonical – a move that one would think would be well received. This would make Canonical even more transparent. So please disregard the commentary by folk who assumed that the public discussion of Ubuntu development would somehow change. """ http://www.markshuttleworth.com/archives/1207
"You trust us not to screw up on your machine with every update." -- Mark Shuttleworth
That's not the same as "I trust you with my personal information." No matter how trivial, it's still personal information.
Seems like this could be a potential security risk, as well, although I'm having trouble articulating it.