There's a theory that customers who are disappointed at first, but receive good service to make up for it, are more satisfied than customers who have a smooth transaction each time. Also, you will tell more people about a bad transaction than a good one.
I don't think FFG wanted a negative reaction, but it might work in their favor. Red tendrils of negative publicity are spreading to board gamers and card gamers, some of whom would never have noticed or cared about an RPG who now might take a peek in. By the time those groups arrive, I think the popular opinion will have softened quite a bit.
I think even if they had prepared a really thorough preview of the game, rather than describing the various elements in vague terms, there would have been just as much shock and disappointment. A lot of us feel like WFRP is in our blood... and then we saw pictures of this weird alien thing.
If you read the promo material again with an open mind, it seems to be doing what it's supposed to -- which is to introduce a new RPG. We're only seeing some of the components, so it's impossible to get a sense of the system as a whole. That's the nature of a product announcement. You can't spill all the beans at once.