Well, in my humble half century of experience, it has usually turned out that people who feel the need to keep everything secret generally turn out to have something to hide.
This game will probably never evolve into the game that was envisioned. It appears to be quickly turning into an arcade console game with no soul. I believe the reality is that this game never received the funding required to create the vision so the vision has had to change. I also believe the engine and p2p system has been a much bigger obstacle then will be admitted to. These are just my beliefs and I'd be happy to be wrong but all this game has become to me now is a placeholder until the next big space game comes along. The visuals and sound make me come back for short bursts but the gameplay makes me leave. They give me no reason to feel excited about their product. They give me no glimpse into ED's future and what it has in store for me so I have no reason to believe in one other than I can soon play it on 4 different platforms. Show me glimpses of David's awesome vision. A 5 second glimpse of an atmospheric planet, floating through a gas giant storm, stepping out of my SRV to examine a strange object or even the horrors of being pulled into a black hole of which there maybe no escape. Make me excited and I will happily sit back and wait like I do with other products I invest in.
So to answer the original question, I believe that, if you have something great to show, you will show it, if not, well......you let your customers dream and speculate about it, which in the end is a recipe for let down and constant complaining on the forums. Cheers!