Because that’s how they were designed? Same reason why some have power set pets and others don’t. Why some have channeled based powers while others don’t. Why they have different PIs. It’s how they were designed.
I also think that very few, if any, of the launch powers had combos. In my memory the sure didn't. Then again, I don't remember if light was even a launch power, let alone celestial or the rest.
I believe light came right after electric, but that was so long ago... It wasn't a launch power, but came out fairly soon after release. Fire, ice, mental, gadgets, nature, and sorcery was all we had at launch.
Nature was launch? Did they revamp it? I don't remember the animal forms at launch. I know Gadgets changed, because my character was gadgets and had the boxing glove, which isn't there anymore. I only played beta and a month or two after launch and then left for a long time (8 years or so). Came back to so many changes that it was like a new game.
Yeah nature was drastically changed. There were actually more animal forms at launch. Pterodactyl, wolf, dog, gorilla, and bug form. Pretty sure there was only a few that were supercharge based, maybe just Gorilla form? I never had a serious nature toon, but I do know they cut a few different forms from that power. Maybe someone else can answer or correct me. Boxing glove moved to the Iconic Tree.