See..there are pros & cons for this strategy. Good thing is people may be eagerly waiting for the product to come and when it comes ...there is just sale n sale..Also..company gets an insight about the success or failure of the product through audience reviews. Higher number is towards the success..then it should be launched.

Cons can be....Since the product is not available in the market...people go to buy and seeing the non-availability ..they may either go for the substitute or may make a perception that since this is not available in market...why search for this...

No any strategy can be bad ..if implemented properly..

Now a days, a fundamental requirement of all types of business, majorly SMEs who doesn't have big budgets for advertising is to build an audience first and then introduce the product and services on the second place. Because building an audience first, will bless the business with "pre-customer" database, the audience would have already started liking the product and service which is yet to be launched, they would have built a trust in your business. Now you Just have to introduce your product and services to them and you are done, see your company grow.
And it can be can be done through "Digital Marketing" because it can help you tap, larger market and with very simple methods you can build an audience with you own for your business with blog writing, serving the audience with information on a consistent basis, so that they'll tell you exactly what they want to buy from you, looking after your online reputation( A content management system, email marketing, social media) can be the tools for that.
So start building your audience, because in this modern world only innovative ideas or constant believe of people in you can give your business a competitive strength.