To your second point, I have grown up with smartphones around me for close to half my life and in my peer group it isn't considered rude to occasionally check your phone and maybe peck out a quick response. By contrast, I've found that people with smartwatches are often looking at their watch, which is a gesture that is hardwired in my brain to mean "what time is it"/"I'm in a hurry"/"you're wasting my time". It's a very subtle thing, to the point where it has made me mildly anxious about interactions without consciously understanding why. If smartwatches really catch on, it will take time for me to mentally re-bind that gesture to mean something less rude.