I agree Bosworth's hotter than Kidder, but so is Eva Marie Saint even at her current age. In fact, I'd rather see Frank Langella in a slinky gown than Margot Kidder.
To be fair, in Superman I with the right cinematography and lighting and such, Kidder was marginal. Even at that, Ursa got it right with the "what an undemanding male this Superman must be" quip.
As for Parker Posey, I'd have thought she'd be a perfect Lois herself. I can only guess she's considered officially "too old" now by Hollywood standards.
I like Parker Posey, but she's not Lois (or Miss Teschmacher, for that matter). She's just too edgy. I was skeptical of casting a bottle brunette, but the look worked right with Bosworth.
For all we know, there's no such thing as Kryptonian weaponry anyway. Unless interlocked, spinning hoola hoops are weapons.
Think "Phantom Zone Projector", with modern special effects.
As for going to Krypton, it was a dumb idea if you had time to think about it.
The fallout with Lois and the kid and such makes sense if you accept the "Superman goes away for 5 years" premise. It just never rang true with me. Maybe they thought it was necessary as a metaphor for getting us to get past Reeve, but then they go out of their way to mimic Superman I.