Ya know its funny. Venom is one of my favorite marvel characters so i guess im biased. But first and foremost there is a big difference between Venom and every other spiderman villian. Venom is bankable. What that means is Venom can appear in a spin off movie, a solo movie. Goblins dont work well without spidey, niether does doc ock. Do i think a Venom movie spinoff is a good idea? no, not at all. I dont think an R rated Venom vs Carnage would be cool nor would Venom vs some random baddie. But the bottom line is people who do not breathe for the comics as most of us here seem to, know who Venom is. They like Venom, are they familar with his history, motives, yadda yadda, maybe not past what they saw in the 90s cartoon. But theyd still pay to see him. I know way too many people who are hyped to see spiderman 3 because they want to see Venom. Sorry to Sam Raimi, but no one, no one, gives a s**t about the Sandman. No one. I'm sure some of us here might, thats fine. But your average movie goer isnt thinking "Hmm the Sandman, i gotta see him".
Bottom Line:
Venom = Bankable
Every other Villian= not so much
Again not saying a solo Venom movie would be good at all, just saying.
OH and as for "well the skelton scene would rule"
you mean to tell me if you saw Brock inside Ravencroft walking down a hall and in one cell we see Doc ock sitting in the center with his arms stretched out individually locked in the room you wouldnt not freak? With an easy explination by someone saying he washed up on shore? Then being lead to his cell with Kassidy. Fans would eat that up.
I get the posion taking a person over stuff, its cool, works for the film, but its not the only way to go, just in Sam's mind it might be.
/rant