Sounds like a crappy program. I just went to check to see what the deal is with Discover, and there aren't any where it is 1:1. There are a lot of $20 for $25 gift cards, and $40 for $50 GC, as well as some 20:40, 30:60 and so on. But yeah, with yours, a GC does not seem to be the way to go.
ETA: I was thinking you were talking about partner gift cards, where you can get a $25 gift card for Chipotle for $20 or something. But I think now that you were probably talking about getting a AmEx gift card of equal value or similar instead (and yes, Discover is the same way).