How do characters move to locations
The equip cost is often a balancing knob for equipment, as it limits how quickly you can have them up and running
Maybe the designers decided that they could only accurately reflect these characters by spreading them out across the color pie, or they felt some obligation to get green in on the action somewhere
It is a celebration of Disney's characters, and Han Solo and Iron Man are not Disney characters even if Disney owns the rights to them
If you have a Saga thats particularly powerful, and you dont want it to go away - for example, Wilds of Eldraines Three Blind Mice , you can keep it hovering between that second and third chapter, to keep making tokens of powerful creatures
You can burn a 'walker and shoot a dork, and so forth