You can tell a punching robot story with Wonder Woman. You can tell a punching robot story with Superman. You can tell a political story with Wonder Woman. You can tell... you can tell another punching robot story with Superman.
Who's the limited character?
The thing is, he doesn't have to be. Clark is a friggin' journalist. There are all kinds of stories they could do from that angle. Investigate and expose something as Clark, do something more directly about it as Superman. There's a lot more good for Metropolis and the world he can do than punch robots, and you don't have to mess with the fundamentals of the character, since it'd just be using something that has been there from the beginning. You can explore any issue with this character that a crusading and idealistic journalist could possibly get involved in.