I know I've talked to all of my couples about this and had a whole hearted agreement from them that their ceremony will be unplugged and that I won't have any issues. From a photographers standpoint its just annoying, and then you have hurt feelings if you didn't get shot A or B because Aunt/Uncle Bob were using their flash while you walked down the aisle. Trust me, it sucks.
Now I'm on the other side of the lens, literally and figuratively, and while I see the excitement in going to a wedding and wanting to hold onto that moment forever I would much rather you hold onto it through the trained and professional eyes of my photographer.
I don't want to have to go through my wedding ceremony and see that my family was too busy taking pictures with their iPhones to enjoy the fact that I was getting married! I definitely don't want the risk of losing shots because so-and-so decided to be a "professional" and shoot with flash.
I don't want hurt feelings or a sad photographer, because I didn't scrape the bottom of the barrel with hiring her. I went through over 100 different photographers local and out of state before deciding on a who I would trust with this day.
And that's why our ceremony will be unplugged and if I see my grandmas phone come out, I will walk down the aisle and confiscate it. Kidding, but seriously, I will cry ugly Kim Kardashian tears and you'll have to live with that for the rest of your life.