I don't think it's all that silly. It's happened before in film. And considering most Superman fans (and even a fair amount of people who worked on the films themselves) don't really remember Superman III or Superman IV, nor do Supermans III and IV seem to have any continuity with I or II--why not ignore them?

Personally, though ,I would have preferred that Singer have adapted "Secret Identity" if he wanted to keep Superman grounded and attack many of the same themes he attacked in the movie. That graphic novel is one of the purest, most inspirational and heartfelt studies on Superman I've read.