Cinema history is full of them.

You could argue that the beginning of Oz's story isn't too unlike Aladdin in basic story structure: poor con man who wishes to be great, thanks to magic he gets that chance, he lies and feels himself too much...

... but you need redemption for it to work. And to have redemption, you need:

1. Someone he has legitimately wronged, which requires a relationship. He has no real relationship with Kunis before she freaks out.
2. A moment of clarity where he realizes who he really is and how he needs to change. Michelle Williams reveals right away that she knows he's a liar and a con man, but she doesn't care, so neither does he. She just needs a male figurehead. Thus he never needs to change, stop lying, or have an emotional breakthrough where he acknowledges he in no way deserves any of this. He spends so much time saying "I can't" that he never once says "I shouldn't."
3. A worthy adversary to prove the mettle of your character. This is more the flaw of prequels in general: he can't kill either witch. So the big victory is... he scares her real real bad. That's the final battle: the bad guy gets frightened. And since the bad guy is the person he "wronged," he never has to redeem himself to anyone of real consequence. The finale is that the liar wins with a lie and continues a life of lying where he now is rewarded for it with gold and a beautiful woman.

There's really just no good way to make a hero story about a character who was never meant to be a hero in the original film in the first place. The whole message of Wizard of Oz is that hero worship is pointless: you possess what it takes to achieve your goal, and you have all along.