Out of the hundred angles you could take on this story, "A new iPhone feature poses a threat to opinion pollsters" would be way down on my list of possible headlines. I'd start with "A new iPhone feature will make life measurably better for millions of users" and work my way down from there. All you need to do is remember to turn it off if you're expecting an unusual call, eg. if a plumber is coming or you're waiting for a tow or something.
Remember, kids: legit calls will leave a voicemail. So if it's your doctor or something, you'll still get the news if it's important.
If you want to be nice, take a few minutes and update your outgoing message to say, "Hi, I have my phone set up to send all unknown callers straight to voicemail, so if this is important, leave a message."
And as a bonus, iOS's voicemail transcription is pretty decent. I already manually ignore unknown calls, and 3 seconds of reading the transcript means I don't have to actually listen to a recording of any bullshit sales calls. ("Please call us immediately regarding your car's warranty!" -- seriously, fuck you.)