If the end result is the same, it seems like the movie has just cost a lot more than it would have otherwise.
Not a lot more. Rodriguez's latest movies have hundreds of EFX shots in them; you're talking about a drop in the bucket. For the buzz about "Jessica Alba naked" gets you it's worth what it cost if the actress refuses to do nudity.
Jess isn't much of an actress, but she's popular & known for being sexy. As mentioned "Into the Blue" might as well been called "Jessica Alba's Ass" because of how it was filmed. Alba almost always refuses to do nudity, even when it would make sense for her character to have a nude scene. She also refused in Rodriguez's "Sin City" where it would have made sense since her character is a stripper and it's
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supposed to be a big shock when Mickey Rourke (& the audience) realizes that the cute little girl who's life he saved grew up to be this stripper that we've been watching.