Actually, Dean made an excellant Clark Kent, his Superman was only so-so.
The two things that disqualify Dean for such a role in a major movie would be his age (he's in his forties and that would never do for the movie franchise people); and his height. Being barely six feet tall he just isn't impressive enough in costume. He was perfect as Clark Kent but Superman can't be looking up at his cast mates.
Tank (who would love to see Teri as Lois but knows that TPTB aren't looking for a mature, established Lois Lane, ie: she's too old also)
