It depends. It seems like the goal here is to make the airlines money while still making it seem to the passenger like they've gotten a decent deal. A less frequent traveler who doesn't know that $300 is a low-ball offer might be perfectly satisfied with that, even while a more frequent traveler would laugh at such an offer.
There's no objective measure of the feeling of "getting a good deal". It's entirely subjective and depends on what the customer values, as well as how much information the customer has about similar transactions. Obviously if the customer later gains new information that suggests they could have gotten a much better deal, that's a negative, but part of figuring out that optimum deal point is figuring out the likelihood of that, as well.
