* Let the public markets know there's something good in the pipeline to keep the stock price as a decent level

* Let the distributors / carriers know (+ no worries about leaks)

* In some ways, it's better than the alternative of a leak, where all the marketing messages come from some crappy blurry cam mixed with a bunch of fake images

I agree it's a little risky from the consumer's POV. Bear in mind a couple things though:

* Even for consumers, when it gets released, they feel more positive towards a product they've heard of previously

* It's possible that the interest will be maintained over that period, although this is a stretch for anyone that isn't amazing at marketing.