The thing that kills me now a days is the fact that if you don't fly JetBlue or SW, you also have to pay extra for your bags! With a family, that's at least $100 each way added on

So watch those United, Delta and AA fares.
You pay for checked luggage on WN (Southwest) and B6 (JetBlue), as well. It is just included in the fare.
A major reason the legacy airlines continue to use the a la carte method of baggage fees is due to federal taxes.
Fares are subject to additional taxation, while
fees are not. Thus, an airline could bundle bag fees into the ticket price (like WN and B6), but it helps reduce overhead for the airlines by keeping them separate.
There are other reasons, as well, such as customer request (businesses prefer to have baggage fees separate to make the tickets lower for their frequent fliers) and the business models of the "low cost airlines", a name WN is growing out of (the main reason they keep baggage fees included in the fare is the perception of "free" bags in capturing and keeping market share of the general populous).
All that said, I have advice for the DIS Board population. Find out what airlines you generally fly on your annual pilgrimage to WDW and DLR. If it is a legacy airline (and some low cost airlines), look into their co-branded credit card. It will waive bag fees, permit earlier boarding, and provide additional ancillary benefits, making the annual fee worth the cost.
It really is a complicated pricing model, and each airline segment (low cost, legacy, charter, etc) has their own strategy based on the client base serviced. Just because bag fees may seem like "extra" cost, in the end they likely aren't.
*This defense of the airline industry is brought to you by.... *
