Apples and Oranges, Gavagai. One is an online subscription service at a flat monthly rate hosting hundreds of players at a time across four main arenas, three special events arenas, the Cesspo...er, I mean DUELING Arena and Axis and Allies. I don't pay any more per month when a new patch comes out.
The other is a primarily offline simulator with multiplayer capability. My beef with their DLC is not so much that you're paying to add the planes to the game. It's that they're already IN the game. The updates add these new planes to the game and you can run into them flown by AI pilots. What you're paying for is to make content already present USABLE by the player.
If you have to pay to fly it, then you should be paying to add it PERIOD. None of this free for AI pay to fly BS. Even the "official" add-ons for the CFS series you had to pay to even GET the aircraft. And for that matter, you shouldn't be able to fly in a server environment with people who haven't paid for that plane, too. In the $15/month Aces High, everyone has access to EVERY plane. And before you get smart and talk about perked rides, EVERYONE HAS ACCESS to them. I don't need to pay an extra $5 to roll an F4U-4. How would you like it if Aces High had THAT sort of business model with its perked planes? Wouldn't YOU feel a little bit ripped off if you had to pay an extra $10 to be able fly a 262, when the flight model ALREADY EXISTS in the game and you're watching other people zip around the arenas in it?
If they're going to charge for extra aircraft, then release it AS an expansion. Pay to ADD IT, NOT just to fly it.