This is not a "cost" because no one pays it. The 25BTC are created out of thin air as a reward to the miner. I don't see the relevance of this metric to your argument, but I hope that you will edify me.
You can't create money out of thin air. It's the same as with dollars (and any other currency). The more money you print the more you will devalue each individual unit (due to inflation). In Bitcoin this currently doesn't matter as deflation is much higher than inflation.
