[Crazy Jetty]

I think one of the difficulties is that odd thing that's really hard to describe, known as presence.
Certain actors just have this... presence... about them. And it gets really difficult with casting female characters because there's far fewer actresses who have a presence about them. Does that mean they're bad actors? Not nessisarily.

As an example... Sigourney Weaver most definately has presence. You know she's around. You know she's there, and you just respect her for simply being there. There's just something... powerful... about her. Flip over to someone like Jennifer Aniston... she just does not convey that kind of air about her.
The problem comes in with a lot of female comic characters *do* have a presence. People like Wonder Woman, or Invisible Woman. When they burst through a wall and beat the badguy, you're supossed to feel every bit as confident and safe with them as though it were Superman, or Captain America. Even when they aren't, you would just feel like you're safe in their presence.
That's *very* difficult to find in male actors. It's almost impossible to find in female.

And that's a big part of why Jessica Alba fails as Sue Storm. To me, she just does not carry that same kind of presence that her character has. It isn't so much that I feel she did a bad job as Sue. Just was a mismatch.

Back in the day, Sigourney Weaver would have made one hell of a superhero, or villain. She'd have been the ultimate Star Sapphire.