A phone could have the same issue? If someone is unable to wait a few seconds to finish a sentence, ask for a moment and check if it is important, than I think that is not the watches problem and a problem that would come up via other devices anyway.
Could, but I've almost NEVER noticed it with phones, and I notice it every single alert with smartwatch wearers. It's like a pavlovian response. With phones, people either wait to take it out of their pocket, or they do so as they speak. I'm not sure why the wrist action causes them to pause mid-word. It's extremely strange.
Granted my sample size is small; just a few folks I know at work and personally who have them. It's uncanny though.
Well I have noticed worse with phones. People having their phones out during a conversation and starting to reply or look at something on their phone while "listening" to me talk. This was at school, however during the summer when I work people with smartwatches I would notice would typically excuse themselves if they noticed an important phone call or message they had to deal with. They would always finish talking though before they even checked if it was important though, unless it was buzzing like a phone call.
But like you said, this is also my personal experience and my school and work environment may be much different than yours, and even have a different kind of cultural approach.