Perhaps something is lost in the translation, but I can't agree with you that Visconti, at least, has no sense of the tragic. (I'm no Fellini expert.) One only has to watch Death in Venice to understand that (whether the film is to one's taste or not).

Perhaps you are joking - I don't know anyone who would say Fellini and Visconti think the world is a comedy.

In any case, it's rather irrational to make such gross generalisations.