I don't know it of course, so it is just a guess. But it would kinda explain all of this tight-lipped marketing by Bethesda perfectly. It seems most people feel that combat is so far the best part of Fallout 4 - at least definetly an improvement over Fallout 3, which is pretty much what was shown for months before the release. The rest of the stuff, was almost never shown. No details of the plot, companions, dialog, quests, or the factions really. And, what surprise, it is one of the main point of criticism, at least by some reviews and players. Not to mention the animations and a lot of what seems to be directly recycled stuff from Fallout 3. As one example, the whole visual damage mechanic on NPCs seems to be a DIRECT copy from Fallout 3. Like all of the kill animations, heads and limbs STILL cut off on the same "joints" like in F3, which I always found extremly stupid. I hoped they at least improved on the visuals of combat here.