I like the idea that they're intentionally holding back to avoid showing their hand too early. When you think about the presentation, they showed just enough to stymie any leaks coming out of the supply chain when they start to produce more watches.
1. We know what it looks like, in all form factors and styles.
2. We know a basic set of functionality, that is, they've led Motorola and Samsung to believe that they're heading down the right path.
3. Most importantly to Apple, they've led Google to believe that they're also on the right path with Android Wear.
It's common knowledge that Google pretty much immediately switched directions on Android as soon as they saw the iPhone reveal in an effort to get their OS touchscreen ready, and even then the first real product didn't get a release until 2008. What's going to be their reaction when the Apple Watch is fully unveiled 2 weeks before launching to millions of customers world wide and they're caught completely flat footed?
Furthermore, consider where Apple holds its competitive advantages. To this day, they've excelled at miniaturization more than anyone else. No one has been able to match the the performance and size of the iPhone 4" form factor and maintain the same battery life. Their competitors were lucky that in the case of phones, larger screens are more appealing to customers and were able to work around Apples advantages via pure brute force (i.e. having room for bigger batteries, using hardware to make up for the flaws in Android software performance issues)
When it comes to watches, how it looks is king more than anything that has come before, and you can't simply make it bigger to squeeze more battery or performance in to increase appeal to customers. In fact, the watch form factor essentially relies on Apples greatest strengths: designing stylish, desirable products better than anyone else in the industry; and designing powerful, miniature electronics that sip power.
It will be interesting to see if anyone can catch up to Apple at the same rate that they did in smartphones.