So it's like "hey guys, we have something pretty big to show you but keep in mind that everything you're about to see will not be in the actual game, because ~alpha build~." Then what was the point of that showcase if nothing of that made it to the actual game? It's not the same. Cutting a few cutscenes and dialogue is one thing and it's expected, but cutting a whole quest with a whole new gameplay feature that they were so proudly showcasing? It's our fault that we fell for that? Ok, whatever you say.
That 'showcase' was a prototype test to two rooms full of people (maybe more unseen).
It was to get some feedback early enough to do something with the feedback.
BioWare never released that demo footage.
So why are people building their expectations on a pre-alpha prototype that was not shared?
People watched some footage taken by a couple of people on their camera phones
and decided that was pretty much the final version?
Is that their fault?
Yes it is, pretty dumb.
It's also completely unreasonable to hold BioWare to that prototype which they did not 'showcase'.
(Incidentally, much of Crestwood remains (the weather is different) - the rift underwater, the cave up to Keep, the trebuchets are in Haven now - who knows what will be in DLC...)