Eh, I'm not really for that. I think Superman should be colorful and entertaining, but that doesn't necessarily mean it requires a campy, buzz-killer like Mxyxptlk.
I've felt that the joy has been sucked out of this franchise. Superman is inhuman and borderline creepy, he has no real adversaries to fight, nothing to get your blood pumping, etc.
Goyer should tap in that feeling, that childlike feeling of wanting to be Superman. Someone people can relate to. I don't want to see Superman sulk outside Lois' house like a creepy perv or fight Kevin Spacey over land disputes.
I feel, personally, a great way to address this is with Kal-El's Kryptonian heritage, but it remains to be seen if Goyer is thinking the same thing. Regardless, we need to root for Superman again - and that hasn't happened in a long time. He needs to get the shit beaten out of him.