Re: Ignoring Superman 3 and 4
It was a bad idea because Singer therefore muddled the exact sequel his film uses as a springboard for its own narrative purposes. The film suffered from cherry picking elements of Superman 2 and discarding others, leading to a lot of confusion over exactly which film it was a sequel to, Superman or Superman 2. Singer should've ditched his film's connection to Donner wholesale or he should've taken all the films into continuity.
A thing isn't beautiful because it lasts -- The Vision