I generally agree with you on the issue of consumer demand and companies having to answer to it. I guess where we differ is primarily that I think the onus is on the game writers and consumers to become informed about the badly designed product.
As I said, I think there are some people that, if they had this information ahead of time, this product would still be "ok" for. But then again I can also realize that this is because I have a different standard for what I consider "unplayable." I played a ton of games in the 32 bit era for example that had framerates below 20fps on ona regular basis. Hell, many of them that was the maximum framerate. I'm the guy that didn't really have a problem playing Enslaved while there was a ton of general bitching and moaning about it. I literally almost didn't recognize it because 20-25 fps doesn't bother me that much. I certainly don't consider it "unplayable."
In this case, it is certainly worse that than, but it's primarily in towns and primarily after fast traveling and even then only for some players, correct? I think it is a bit of hyperbole to call that "unplayable." For the consumer that has only a PS3, in fact, I think that might be a worthwhile trade off as long as they weren't decieved about it ahead of time.
Again, if they were, that is a problem.