I agree. BC does not offer a fitting conclusion to the Raimi films IMO. I mean we're talking about a movie that could go KLH meets Lizard and we're hearing rumors it is going to be a mix of Superman IV and the Elektra storyline? That just sounds lame, IMO.
But I do like the BC character. However, the way the series has developed, I'm not so fond of using her. If they had planned this and not put Gwen Stacy in SM3, but rather made that character Felicia Hardy and make her a real temptress, so that MJ's suspicions were somewhat justified, it would have made MJ look better and done a nice set-up for SM4. However, they went with wholesome Gwen, so the idea of a new "Other girl," even if this one is a fatale as opposed to another girl next door type, seems off-putting.
But I think the BC character can be written well for a fatale. The early stories she had in the '80s before he revealed he was Spidey to her were playful, somewhat full of innuendo in a 1940s movie kind of way (they were having sex without having to talk about it) and created some interesting stories in that he loved her but would not unmask himself. Recently, since the sexualization of the character and turning her into a crazy-ex, Kevn Smith and Dan Slott restored some humanity to her and made her interesting again before this BND nonsense. KS reenergized her backstory and relationship with Peter and Slott and Mark Millar made her Peter's closest costumed confidant. That is a great angle, but again that would require years of backstory like in the comics to reach that point where she is Peter's unrequieted confidant that MJ doesn't trust.
None of that is accomplishable in a film that should be winding down the stories. However, if she has to be in it, I do think a good actress makes her better. The best fatales, Barbara Stanwyck, Mary Astor, Rita Hayworth, Lauren Becall, Gloria Grahame, Jane Greer, Gene Tierney, Ava Gardner, Kathleen Turner and Kim Basinger were all great actress or at least very good ones who played their parts with allure, sexiness and creativity.
Good actresses make great fatales. Casting a former playboy model (which I found out the Diora girl is) just because of her comic resemblence is silly. All women, including MJ, Elektra, Sue Storm, Rogue, Jean Grey, Emma Frost, Wonder Woman, Poison Ivy, Harley Quinn....deep breath...etc. are drawn today in comics with that unbelievable body. Few actresses have it. Of the great fatales I named, only Gardner looked like that. In fact the first two fatales I listed weren't even that physically attractive.
It is how the part is played.