The marketplace has spoken on flat-fare pricing. Every time an airline has tried to move in that direction, they have been hammered by passengers fleeing to other airlines. Every time they add an a la carte fee, the press grumbles, but the public pays. Southwest is a very interesting counter-example---they are pricing higher on average, but sprinkling in deals, heavy spending on ads proclaiming themselves a bargain, and trumpeting "free" (really, *included*) luggage.
At first, I was convinced that wasn't going to work. But, now I'm starting to see it in the same light as the "free" dining promotions that Disney runs. In many cases, "free" dining is a *worse* deal than the straight room discount, but people fall all over themselves to book it, because they eat for "free" and they don't even bother to compare the all-in prices for OOP dining (or a paid plan) plus a room discount.
I'm starting to think that's the same market that SW is trying to develop; a set of people who automatically book with them, even at higher fares, because bags are "free" and so it must be a "deal". But, even SW is starting down the a la carte road with ECBI, so perhaps they're not sure yet either.