5. He's Not Evil Enough / Too Soft
Marvel StudiosSimply put, for a villain or antagonist, Loki just isn't evil enough. He's too soft. Aside from the aforementioned mummy's boy issue, Loki has also shown too many signs of guilt and emotional weakness to be truly considered an outright villain - and that weakens his stance as far as viewers are concerned, as they're always liable to think he won't see a plan through or will end up helping Thor. For example, on top of Stark Tower in the Avengers movie, whilst battling his brother, Thor very nearly got through to him. And when Thor and Loki were battling Malekith and Kurse (an event that, in itself, epitomises why Loki isn't evil enough), Loki took a potentially life-threatening wound to his gut in order to save Thor (granted, he faked his death and went on to usurp Odin as Asgard's king off-screen, but the fact that he took the wound and defeated Kurse in the first place was a sign of weakness). If, as expected, Loki re-emerges as a villain in future movies, he needs to be far more clinical when it comes to being evil.