I didn't the last time I went on vacation in Europe. My cell phone carrier also is atrocious and charges usurious international roaming charges, so that was a contributing factor, but it's really nice to unplug and go off the grid on vacation. You just have to do things the old fashioned way - print out your reservations and itinerary, get some maps.
20? I recall going to Europe for two weeks in 2006 (BMW European Delivery). Didn't bother bringing my dumb-phone. Just had a camera. I drove 2000 miles around Western Europe, 6 countries, had zero hotel reservations before I left, and had no problems whatsoever. This was in April so just popping into a hotel and finding a vacancy was not a problem.