People say VALVe's way works for DLC, but that way involves paying more for microtransactions than one would pay the flat 10-15 for map packs. On average, a typical TF2 user is spending much more than 30 bucks just for fucking hats.
So let me ask you guys this, would you rather it stick with the 15 bucks per pack or would you be open to hundreds of microtransactions in which you can spend much more money on shit you don't need, while being given maps which are always meant to be free?
Side note, I'm not bashing VALVe. They are the only ones left who care about PC gaming, you hear that Blizzard?! Release Diablo III and I'll change my mind.