If you don't make copyright contagious under derivative works then people can just change a few things to get around copyright.

Also, do you really want a world where big film studios can just adapt books of writers without compensating them?

Surprised to see this level of discourse here on HN, reads like a reddit comment.

Copyright sucks, and Disney is bad etc, but how is using StarCraft and its assets in your random AI game okay?

I mean, creators should be allowed to exert control over how their assets and brand are used.