The compelling reason that I hear most commonly is an urgent need to know why your phone just went off. As in you are driving and probably shouldn't check; let alone reply to that text, but you will risk life and limb to check that text. Seriously, you couldn't wait until you are at least stopped at a red light and get honked at as it turns green and you aren't moving because you are engrossed in an epic text conversation about the latest internet meme.
I came across an article on gizmodo that harks the need to know sentiment to which I commented on;
You need to know what just happened? So you're the idiot that causes unnecessary traffic jams and accidents because you just needed to know as you swerve to your and other driver's death? You must be the moron who is trying to reply to a text while riding his/her bicycle and gets creamed by a bus because you just had to know, and you must be the colossal buffoon who stepped off of the curb to cross the street when the cross walk is five feet away and you are hit by a cyclist replying to a text into traffic who is then struck by the motorist checking email just because you had to know.
As a watchmaker I already do not want to see the precious wrist real estate taken up by a gaudy gadget with a tiny screen that should tell you that you are a tasteless idiot, but instead pretends to be convenient by catering to your addiction of social media and messaging. If you ask me what I think about smart watches, now you know.
Quick little update: Seems the author of the gizmodo article Eric Limer has removed my comment. Apparently he is the sensitive sort who can't handle people that can see right through BS.