RexRox, I guess it depends on your perspective.
I appreciated that the feature was on by default after the update since it meant that I didn’t have to do anything to start using it. I was also aware of it because, before I updated my device, I took the time to read the information that Apple put on their web site that explained what new features were being introduced with the new OS and I learned how they would affect me. Also, I don’t think Apple is aware of how everyone configures their devices. In your case your devices, as well as your wife’s, share the same Apple IDs for iCloud services. Most people would keep those separate I think.
I understand your motive was to share Calendars and Contacts but you can share editable calendars amongst separate iCloud accounts.
iCloud: Calendar sharing overview
Also, the new Family Sharing feature actually creates a shared Family calendar by default when it is set up.
http://www.apple.com/support/icloud/family-sharing/
Contacts, on the other hand, aren’t sharable, would be nice if they were, but it is very easy to send contact cards to another person using share sheets.
There is a workaround involving creating another iCloud account just for Contact sharing. You can read about it here: http://www.macworld.com/article/2013415/how-to-share-family-contacts.html
Of course, as I said, your perspective is different and Apple provides a way for you to express your point of view.
https://www.apple.com/feedback/