Because now they haven't leaked details about the game that some players will take as promises. Like dawnguard, "upgradeable forts" the forts were upgradable. Just not the way most people wanted. There are only like four confirmed details. 1st db, hm, solstiem, hm oblivion realm.
Marketing wise isn't doesn't make very much sense to me. But I'm not a businessman so ill leave that up to Beth. For those of us that do follow these topics, the wait is excruciating.
I think Beth is confident in their product, and when it comes out, the product will speak for itself.