I remember being very impressed with Apple's knowledge navigator video back in 1987 (yes, I remember 1987, I'm that old). Produced during the bad old days of John Scully's leadership of Apple it was the last stand out example of Apple doing something they absolutely never do today, produce a concept.
Concepts and their bastard offspring, beta releases, are rampant in the IT industry. Everyone is keen to tell you what you'll be able to buy from them at some undefined point in the future. The products actually released never quite match the concept's hype, a bit like the car industry.
This doesn't seem to their production. Possibly the concept producers believe that our post-purchase rationalisations will lead us to kid ourselves that the difference between what we end up buying and what the concept promised us isn't the grand canyon sized gap that logical consideration would confirm it is. This isn't an unreasonable hope, we're all terribly good at kidding ourselves.
Apple don't do concepts, it's one of the things I admire about the company. When they launch a product it is, they tell us, finished. In fact it's perfect and absolutely the best thing you could ever conceive of buying. Six months later they launch the next version, which is even more fabulous and perfect and "magical".
Putting to one side the dangers of superlative-inflation this approach exposes Apple to, it's a great strategy. It focuses Apple on shifting what they can sell now and stops them promising future developments that could delay a purchase long enough for a competitor to steal the business.
Internally this also seems to result in some really great products. Apple products have to look and behave as if they are finished, any concession to rough edges would ruin the underlying message.
Google Video, Buzz, Answers, Wave, Notebook, Page Creator...
Now let's look at Google. Google churns out betas and concepts faster than a politician churns out expense claims. Google Glass is a decent case in point. We've all seen the promotional videos and we all know, based on our knowledge of how betas work, that the reality is going to be a lot less interesting.
When released the product won't be finished and polished to the extent that we'd expect if a company like Apple were launching it and will disappoint all but the most obsessive Google fans. I'm sure it'll have plenty of potential but the great mass of consumers aren't interested in potential, they just want products that work.
So why release a incomplete product?
Lack of confidence
You might release a beta because you are unsure how to finish it and want market direction. This is a flawed strategy, early adopters are unlikely to have wants and needs that match the larger market for the finished item. Besides, you should have enough confidence in your own vision (especially if it's a new product category) to complete the product and impose your vision on the market.
Poor attention to detail
Perhaps you are an engineering focused company, bored with the tedious process of rounding the product offering and wanting instead to move onto the next interesting research project. You know it isn't really finished but your unofficial company motto is "it'll do".
Perhaps you know that competitors are working on similar products and you fear losing first mover advantage in defining a new market sector.
Whilst all of these reasons usually contribute something towards the release decision, I suspect that in the case of Glass, it's mostly that Google don't know what direction to take the project and they are hoping that someone (or some large group of people) is now going to tell them.
My guess is that the 'someone' will end up being Apple, the worst possible outcome from Google's perspective.
After all, Apple told the industry how to sell music and videos (after watching others fail to do it properly). Then they told everyone how to build mobile phones (after watching others fail to do it properly). And then they followed that up by telling the industry how (& why) to build tablets, etc.
That's the Apple model, find a market dominated by or opened by companies with an engineering culture (so focused on the next big thing that they forget to finish the current big thing) and then release a product into that market that works properly.
So, here's my Google Glass prediction. After Google release some beta versions that demonstrate some kind of need, Apple will beat them to the punch with a product that actually works.
iEye? iVision? Surely a better bet than the Apple wristwatch project.