And now it has officially been confirmed that this expansion pack adds content to the base game, too:
So if you buy the expansion pack, you’ll be able to craft at least some of the building sets, armor and weapons from it, regardless of the map you’re on.
Is that enough to accept that this is, in fact, an expansion pack or do you want to insist on redefining the meaning of that term because you didn’t get exactly what you wanted?