Same thing happened with Spore as I recall. People made it out as something amazing in their minds and then realized it was just a big casual toy.
Nope. Ever seen the first video they released? I think 2005.
Watch it and you understand the disappointment.
Oh I'll grant that it was overhyped by their marketing and it suffered from a bit of molyneux syndrome. I didn't mean that disappointment was unwarranted, just that some people had built it up so much in their head that they had unrealistic expectations.
The problem in this case wasn't that Spore hyped itself up to death... In fact they systematically stated every single thing in the 2005 video was false as time went on (Even in one interview outright stating that there was no ragdoll or arm ripping and explaining why there are googly eyes on the cells). Anyone who kept up to date with all the videos, which unfortunately can be tough to keep track of, sort of realised the game was somewhat weak unless they were still hoping for some 2005 magic.
-Sadly from what I understand from that interview... Will Wright argued (and Water) in favor of a more scientific Spore but he was outvoted. Frankly it would have improved the game. SURE Spore probably would have still been a weak game but there is something about the majesty of education that can turn everything right.
The problem was that the Spore Fanbase held onto the 2005 video and wouldn't let go no matter what happened. Someone jumps in asking what Spore is about? They will show that person the 2005 video. There was nothing I could do on gameFAQs about it... As soon as someone asked it was "Hey watch this" inspite of the fact that they said the 2005 was false by 2006.
So it isn't Molyneux Syndrome in pure form. They didn't pretend the game was something it wasn't until the end and then go "Ohh yeah, it isn't in the game guys".
In Dust's case... They only really advertised the physics and by all means that is the basis in which you would buy the game. Your not going to buy it for its great gameplay... Your going to buy it because it is cool.
In fact I have to say, dust REALLY, and I mean really, doesn't try to advertise its gameplay almost at all. It just seems to be glossed over. "And get your people to safety, but did we mention you pick up DIRT!?! Yes we COULD show you saving people but we would rather show you this water physics OMG it is amazing!"