The nature of my work is such that I need to be able to be reached in an emergency, regardless of where I am. It doesn't happen too often, and when I do go away, I know that my team is left in capable hands.
That being said, I will check my phone occasionally during the day- let's say a quick glance every 45 minutes to an hour. If there is nothing there, I put it back in my pocket.
There are times when my wife will go off with my older son and I will sit and relax for a while with our little one while he is napping. At that point, yeah, the phone usually comes out just to keep me occupied. However, I do find myself ignoring the phone more often and just watching the world go by when at Disney.
Also, keep in mind that these days, many people use their phones as cameras as well.
As for kids at dinner on the phone playing games... I have a 7 year old with ADHD and ODD. Between the over stimulation of being at Disney, the long days (even though we are the more relaxed touring type), and the fact that his medication is winding down usually about the time we settle in for dinner, keeping him occupied with Angry Birds, Fruit Ninja, Temple Run or whatever so Mommy and Daddy can also enjoy some quiet time - after all, it is our vacation too - is not something I am opposed too. He plays his game, he's happy, and we're all nice and calm and quiet.
We have spent the entire day together at this point, and letting him unwind in that manner is what works for him and for our family. We have been that family that has cell phones out at the table during meals, but it is also the only time we have to catch up on the rest of our lives outside Disney. For the most part, my wife is sending pictures from the day to the rest of the family. As much as we want to get away from life, it still keeps going while we're on vacation.
Cell phones and tablets are a part of modern life. I do agree with the original poster though that some people do take it too far and that in general people need to slow down and enjoy life.