Because the IDW Springer and G1 Sandstorm are the more well-known versions of the characters. Plus, to make the Springer mold into IDW Sandstorm, it would take even more retooling, whereas to make him into a G1ish Sandstorm was feasible. They worked with what they had, and did wonderfully, imho. I would love it if we got Flywheels, and I wonder if Astrotrain/Octor woud be possible from the same mold, as they both turn into flying things and fairly squarish wheeled vehicles. Do as extensive of a remold as you have here on the Springstorm mold, and BAM Voyager triple changers everywhere, and, if you count FP Assaulter, you have everyone!