system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Would Cinematic-Loki have been such a bad king?

Looking through both of the Thor movies and even Avengers Loki doesn't seem to be that malicious of a character. Don't get me wrong, he is ruthless in the pursuit of his goals. . . but he isn't evil for the sake of evil, he simply wishes to rule Asgard (earth in Avengers). Furthermore, he seemed to genuinely care about his family, even if he had to remove them when they got in his way; he also seemed to have sense of honor, if extremely warped. Even going so far as to allow his brother the freedom to return to earth at the end of Thor 2 while complimenting and making him feel better about himself. 

What I'm getting at is, aside from how ruthless he is in achieving his goals he seems to be the type of political, manipulative, and genius (arguable) character that'd make a far better ruler than a hero-fighter like his brother.
gpt
IMO, you can look at how he treats humans for an example of his character. He made his scene, he didn't need to lecture people - he did so because that is how he genuinely felt. Likewise, look at his dialogue with the avengers and see that he truly feels that he is superior to everyone (humans in particular) and that ours is a life of servitude at best.

You don't want a person like that in charge of one of the most powerful armies in the universe. He might be great for Asgard... but he would be horrific for the rest of the universe.