Since it's more convenient for us to fly out of Ontario, CA than LAX, I think the price is fairly reasonable. Flying from the west coast,
DCL puts you up in the airport Hyatt on the night before the cruise. This is probably worth $100 or so. The published rate is $179, but you can usually get it yourself for less. Staying at the Hyatt is really convenient.
I've priced it separately, and you can do air, Hyatt, DCL transfers for less, but usually not that much less, at least when flying from Ontario. I see the extra we pay as peace of mind knowing that they're in charge of everything. If the flight is late (although that's not really a problem flying in the night before), or especially if the ship is late getting back into Port Canaveral. In this case, they'll arrange a new flight, if necessary.
Overall, I think it's worth it for the convenience and added insurance. I'm sure you could do it yourself for less. It's pretty easy to use Travelocity or Expedia and price the whole thing on its own and then decide whether it's worth it for you to make the air arrangements yourself, or through the cruise line.