You're thinking only about the end user - what I'm talking about is more encompassing than that. Toothbrush companies want metrics around their product. Users are going to soon be faced with a choice to either purchase a smart product that measures these metrics or buy the old cheaper one that doesn't. The way I expect mass adoption to occur is from the possibility of selling this data and passing off a percentage to the users. Your toothbrush will reward you for brushing your teeth not just with a nice sound or trivial leaderboard but by real world products, discounts, etc. If you always brush your teeth, you get notified that you can get your next toothbrush 40% off. The company will be able to do that because you gave them far more money with the data you provided them which they could sell to toothpaste companies, dentists, researchers, candy companies, etc There's a lot of parties who might be interested and this is hardly the best example.

Arguably these features provide no value already though but only exist because on some level they are fueled by addiction. It always begins with very little effort and a shitton of perceived value. First time using a drug - little hit, big high. The first day in Farmville, WoW, etc all has this exactly the same. You gain multiple levels, achievements, etc. all in a few hours. This is fun you say. I don't need to do this, but if it's so easy, why wouldn't I? You begin doing it more and more. Just like physical drugs, you build up a tolerance. Those achievements that used to get you excited - don't anymore. 100g? Fuck that, you now want 100000g. You need that feeling of accomplishment but it's seldom found. For each higher tier you reach or better gear you find - there is always something better that is exponentially harder to get. Your addiction has changed your perception of what value is. What you once did recreationally for fun, is now an all day activity where you are mostly unhappy. People have been treated alongside drug addicts for game addiction. As we discover more compelling hooks - active gamification is only going to be more prevalent. The future of course is in passive metrics - sticking chips in things that don't normally have them.