Yeah, I always felt like the frozen veil wasn't all that necessary, but I like it. It's possible that Derek and Alec wanted to do more with it, decided against it but wanted to keep the area in the game anyway. Who knows, maybe they could do more with it in the sequel. All kinds of new waters to discover. More Frozen Veil, maybe a lake or even a place near a terran city. Who knows?
(Edited for spelling)