Rerolling Skin Shards

So I recently got into this whole Hextech Crafting thing, bought a few chests and keys, and got some pretty sweet skin shards. I rerolled three into Beast Hunter Sejauni, which I was fairly happy with. I also opened 3 pretty good shards, Dragon Trainer Tristana, Battlecast Prime Cho'gath, and Astronaut Teemo. So I thought to myself, "Hm, with these 3 valuable skins, rerolling them has GOT to give me something good." So I rerolled them, and beheld the cruelty that is the Hextech Crafting System. Bird of Prey Anivia. I destroyed 2 legendary skins shards and Astronaut Teemo for a 520 RP, not even legacy, Anivia skin. Honestly, there should be some sort of system to prevent this from happening, my salt is real.