Some people may want to know why you want to build a wearable or you may have to sell your idea to the people who are responsible for the purchase. Here are some ideas you may use.
Because, you want to experiment by yourself, because you think that Human Computer Interaction is not a matter of designing the n-th windowmanager, because you feel that enhanced reality is the cutting edge of your evolution.
Some people are afraid of revolutionary or so called products, thus the good news is that the wearable may look like a revolutionary concept but it is actually just an evolution of the computing hardware. Let me explain that : At first there was the Mainframe, then came the desktop computer enabling people to work in their office, latter the PC enabled these people to work at home too, as time passed the portable PC enabled people to work in a Hotel room, or everywhere they could find a power plug ( yes an Osborne or an IBM's convertible were definitively not laptop computers ), at the same time some pocket computers appeared on the market : Sharp PC1500, Canon X07, Casio PB100 then the first one weighted less and less, the second one disappeared but the LCD screen was, with other things their legacy allowing the laptop to emerge, as the laptop went mainstream, its size went smaller allowing people to work in the train, at the library ..., then palmtop PC's such as the HP95LX and PDA's appeared, ( at this time the most successful is the PalmPilot family and its clones ) allowing people to work on the move, so the wearable is just the next step in this move towards miniaturization. ( If you want to learn more about Laptops and Linux you should read the Laptop-HOWTO, the latest version can be found at Werner's Heuser Homepage )
In today's competitive world it is very important to get an edge over the other company, thus for example in a plane repair company the engineers who are using wearables do not waste time in asking for blueprints but instead have the blueprint and the technical data at will while performing their job, thus they will be able to repair the planes faster. You may choose an example in your job.
When they made their first appearance on the market, some products or technologies were, to say the least, less than perfect. This is a stealth menace, if you read Clayton Christensen's book "The innovator's dilemma: when new technologies cause great firms to fail" or Andy's Grove "Only the paranoid survives" you will see that some corporations that relies on a product and that have a king of the hill may fall down because they overlooked a new product/technology that was clumsy at its beginning and was at first in a market niche, then the contender took over the market.
The people who decide to fund your project are not always very found about technical details, thus you will have to use other arguments, otherwise your pet project will be sent to /dev/null. If one reads again chapter 2 of AP Sloan's book: "My years with General Motors" it is obvious that the Wearable industry is going into the same changes as did the automobile industry in the US at the turn of the century : it turned from a Hobby with some small manufacturers to a mass market Industry. It took nearly 30 years to the automobile industry to change, but the wearable industry should have done this changes in less than 5 years, so if they don't invest on this product others will do.