Tracing probably... What other "popular features"?if u "opt out" will many popular features cease to work? probably
Having working GPS/3G does NOT mean recording/reporting the handsets position.
Regardless, I believe the option should be there.
Using a smartphone should not be synonymous to 24/7 surveillance.
With unspecified list of people having access to that material. Plus hackers...
The fact that Apple responded only now - and not in September when first disclosed - when the
US government started voicing concerns is enough reason to believe it was not just "bad judgement" IMHO...