People do get this bit wrong often. The Overmind wasn't meant to be a good guy (Blizz admittedt that they failed to convey this properly, though I didn't have a problem interpreting it), it was more like Nurgle in WH40k: Big Papa Zerg who loves his little rascal alien monsters. It didn't want the Zerg to be toys. Now I'm not saying it's not a retcon, it probably is. But it's not a 180 degrees turn like a lot of other things in SC2 were.