Extrinsic fee is supposed to correspond to the worse case. (if the actual cost is lower than the worse case, there is a refund) For a transfer, the worse case is recipient account creation plus issuer account deletion, so spamming account creation remains as expensive as it should be.
BUT maybe there is a trick, and something complicated related to fees, existential deposit and stuff, makes it necessary to have specific account creation fee. 
Edit: I’ve found Élois’ explanation: Explication concernant les frais de création de simple portefeuille