Venom doesn't need his own movie. What Venom needed was a Spider-Man film in which he was the only villain. Yes, he is one of the most popular villains in the comics, but that doesn't mean he can have a successful movie - quality wise. As Joker said, he is no Magneto. There just isn't enough depth from Venom without the writers having to drastically change him from his comic-counterpart. Also, who would be the hero of the film? Wait, they are going to change Venom into an anti-hero when Venom being a villain (his primary function of being) was already a bang-up job? Presumably, if this is taking place after
Spider-Man 3, how can you have Venom when Eddie Brock got fried via pumpkin bomb?
Of course, it always depends on the writer, but I just can't see it. If anything, this film would hold back other Marvel superheroes from having film adaptations. You don't see WB pitching ideas for Joker or Lex Luthor having their own movies.