I think Sony's marketing strategy with Dreams is that they want as few people as possible to know anything about it. lol
You're right about that when we're talking about the Early Access. They want people who have been closely following the game and people who are really interested in creating to have a better chance at getting a limited copy of the EA for Dreams. Once the full game gets a release date we will see the marketing ramp and MM will finally show the story mode. Plus, there will be a ton of user created content ready thanks to the AE. This my opinion anyways.