First problem, you're thinking of things in literal and fisticuff's terms. Batman(yes even Nolan's batman) could wipe the floor with Joker, yet it's that doesn't stop said enemy from doing major damage and inciting great plot.
Second problem being, you are insinuating lex works alone. Hardly.
Third, you may not have seen this little gem of a story.
[YT]PrcUb8MENAg[/YT]
Many argue it's the best/favorite superman tale thus far(many, not me).
The best part of the whole lex angle is that he hates our hero more than anyone, and it's justified in a twisted way.
-plz don't bring up Bryan Singer, he's a well known hack.
All that being said, I'm not saying I want lex next, but they should mention him. The dude pretty much runs that city.