If no information is forthcoming the developers get accused of not talking to their fanbase. Also it takes time to get a marketing campaign in full gear. The whole point of marketing is to let the public know that the game is coming, generate excitement and when it will be available for purchase or pre-order...
BioWare get criticised for not talking to their fanbase now, but if they do, even in the form of a prototype demo, they get criticised, as in the case of 'Crestwoodgate' being discussed in this thread.
I can see BioWare's line become even more resolutely 'we're not talking about that now...'
Times from launch announcement to shipping date vary (excluding any delays)
- Assassin's Creed Unity was 4.5 months. source
- DAI was 5.5 months. source
- Witcher 3 was 8.5 months. source
- Destiny was 9 months. source
- Skyrim was 11 months. source
This is not the actual launch window, in fact only Skyrim & Destiny, with the longest windows, from the list above delivered on the date promised. These are marketing times of how long these businesses feel is appropriate to market their games.
For DAI, even with the 5.5 month marketing window, the multiplayer was not announced until 10 weeks from the (new) launch date. source
We can't have our cake and eat it.
Either we have highly accurate announcements of content 'at the last moment',
or we must accept a little ambiguity in information if we are hassling the company for 'moar leaks!!'
I expect more of the former, with less of the latter and in a way, I'm sad about that.
The marketing becomes dumbed down, because the audience is sufficiently unable to distinguish between pre-alpha, alpha and beta/gold content.