What's a watch and why would I want one? I mean, why do I need to wear something on my wrist when I have a perfectly good smartphone fully loaded with every application I want? I can browse the web, read books, do all sorts of things.
In many social situations (perhaps you don't often find yourself in these sorts of situations) it is more acceptable to glance at your wrist than to pull out a phone and start fiddling with it. For example, a business meeting, a dinner party or the symphony.
In many sporting situations (perhaps you don't often find yourself in these sorts of situations) it is more convenient to glance at your wrist than to break rhythm to pull out a phone and start fiddling with it. For example, while running, playing tennis or rowing.
I see a few issues here for smart watch makers.
First, people who understand the above situations already have at least one watch. Getting those people to give up something they already know and have probably grown fond of over many years--perhaps decades--for something new, unproven and requiring a battery will be difficult. With the personalization that Apple is targeting they seem to understand and are attempting to address at least one major hurdle: style. How well, we will see.
Second, current watches are either purely mechanical or sip from a tiny battery that lasts years. We can ballpark from physical size and capabilities that an Apple Watch will require frequent charging. If Apple has made a breakthrough of some sort, they were conspicuously mum about it yesterday. People enjoying watches today will have to adjust their long-learned expectations, even if they do get more features from their new energy-hungry watches. How well, we will see.
That leaves us with the current watch-less people such as yourself. Today, they don't find any of my above situations relevant--or they would be wearing a watch. For them, digging out a phone from a pocket might be more compelling than buying a new device they're not accustomed to. Perhaps the new features such as biometrics will sway them to buy a new device. How well, we will see.