it was said once in the movie by Perrry White, it's not like Superman himself changed the motto. the impression i got was that he was excited by the return of Superman (one of the 3 things that will sell papers) and had a lot to say and for the sake of getting his points across quickly, he ad-libbed. am i reading too much into this, yes! it did not bother me in the least, now if Superman himself said something different, then maybe I would be upset, but that never happened.
EDIT:
I understand that the writers changed for political reasons or whatever, but the point is I don't care. ignorance is bliss, I didn't know what they're intentions were until now. since I didn't know, I didn't care, to me it was Perry White ad-libbing. now that I know what their intentions were, I still don't care, I just think they're stupid.