Simply put, you cannot run an airline profitably by selling a transatlantic ticket for $600. the math doesn't work and never has. The earlier, profitable days of air travel, the fares were beyond the reach of most middle class folk, a crappy fact but true, but the fares reflected cost. When the budget carriers came along in the '70's and '80's they took a bite out of the major carriers who responded buy cutting fares to match, hoping to put them out of business. It didn't work. Flying customers came to believe that these below-cost fares were normal. The major airlines finally figured out that they couldn't make money at this rate, so they loaded more passengers into tighter rows increased occupancy and charged for extras. Who's at fault it's not the passenger - it's the airlines for being poor strategists and reacting incorrectly to the budget carriers in the first place.

Having said that if you're flying to Florida for $400 you need to realize that you're getting a deal.