That's how it has always worked.  There is nothing really unfair about it.

First, your pricing depends on the volume of your purchase (although buying fewer returns may or may not have affected your price depending on where the thresholds are).

Second, refunding unused returns had never been Intuit's policy - they used to allow you to prepare prior year returns for free whether you had any leftover but even this policy was quietly changed last year, to many's dismay.  In exchange for that, however, you now only need to commit 10 returns for pre-order to be entitled to the volume discount.  You can then buy just whatever number of returns you may need along the way at the same price during the season; this should reduce the chance of you having leftover returns.

You win some, you lose some - that's the name of the game.