I don't think we should be surprised at the cool response to the Apple Watch among teens.
Let's face it, when Baby Boomers and Gen X & Y were young, they wore a watch to tell time. That's how they knew when to arrive to meet up.
Today's teens its all about text messages and apps that get them where they need to be. And the clock on their phone is likely synced with an atomic clock at some point, so is more accurate than 99% of watches on sale today, including high end Swiss timepieces.
Keep in mind that even a $20,000 COSC certified Rolex is only accurate to -6 seconds to +4 seconds a day. And only 3% of Swiss watches are COSC certified. By comparison, given the sync to an atomic clock, a typical iPhone won't lose or gain a single second during the entire time you own it.
So the average teen has grown up with a different and better method of telling the time and scheduling meetings and events in their lives.
Also when it comes to losing weight, making healthy choices, all that good stuff, they don't really pay attention to that. It's usually the 30+ age group that need to pay more attention to diet and exercise.
I think that Gen Y and older will be quite interested in an Apple Watch. But I don't think Apple should be crying themselves to sleep if a generation of teens that rarely wear watches don't suddenly jump to it just because Apple made a watch.