What you earn vs. what you 'deserve'
If you'll permit me a bit of drive-by cross-linking, this is part of what I was talking about earlier with the "Takers who are also Makers" post. Part of the dependency process is convincing people that they "deserve" far more than they earn, which makes them resent the people who already have those things... and fills them with rage at anyone who suggests they should work hard to get what they want.
Big Government's favorite clients have been told they can't work hard enough to get the American Dream. That article you cited is essentially telling lower-middle-class folk that the American Dream has been moved completely outside of their reach. They can't earn enough to buy a $275,000 house with all the trimmings. Conclusion: America is unfair, the "dream" has been stolen by greedy rich SOBs, and it's time to rally behind socialists who will punish the "thieves" and redistribute their ill-gotten loot.
You make a great point that the American Dream has always been more about the journey than the destination. It's not something that has a specific price tag. But to the extent that it can be expressed in material terms, I feel safe in saying that the "working poor" can afford a lifestyle vastly superior to what the upper-middle-class enjoyed just a generation or two ago, including luxuries that simply did not exist back then. Drop luxuries from the equation, and there's no question the necessities of life are more readily available than ever.
But none of that matters to people who have been convinced that life in this country is a game rigged permanently against them. The Left can only get so far with a dependency class that views itself as dependents. What they really need to win this game is control over the productive - a sense that even hard-working people need some government cheddar just to make ends meet.
For added fun, we could run down USA Today's American Dream shopping list and talk about how the government distorts the price of virtually everything on it...