Apple has been quite successful without letting folks know until the product hits the streets (or close).
There are various methods for such marketing - each have their pros and cons. I think the concerns here was really the change in communication type. That too could have been eliminated with a short note explaining such...
As far as knowing what to develop based on road maps, I'd refer you to the usual case of other companies announcing road maps, plans and promises and then being years late or not doing them at all. In other words, if you are going to announce such things, you have to have a decent record in follow through.