Copyright for nearly everything but software, is primarily a question of "can I reproduce this other person's creative work?". Fair use doctrine is so broad that I think it most everything else falls under most people's accepted "artists deserve to be compensated for their work" gut instinct.

If you're going to save money by not coming up with an original idea for a movie, or video game, or whatever, and then use the public goodwill produced by an existing work to market it, it seems perfectly just that the original creator gets a cut of that action.

Fair use is much more narrow than most people think, it's just that most rights-holders are not very belligerent. For example, streaming video games does not fall under fair right, most video essays critiquing films or series use way too much material commentated for fair right, remixing as a whole is not fair use, and most fan works are definitely not fair use. Legal protections don't help here, but the shit-storms companies like Nintendo of America had to endure when they tried to tighten the screws.

And that's in the US, other countries have similar exceptions but they are also usually quite limited.