If the character stops working and they've exhausted what can be told with such a bland character, then it's the character's fault. They tried the respectable business front. They tried it for almost two decades. They found it didn't work.
Actually, that's a lot like the Luthor in Superboy. And Luthor in the comics WAS about conquering the world. Why do you think he ran for President?
No. We have a Luthor, who by the quotes we have read the character says in the film by set reports and interviews, is jealous of Superman. He is jealous of Superman's power. Also, he resents how much humans have come to depend on an alien. How is that one dimensional?