Seeing what they've done to the Green Goblin and Electro in the new movie, there's no reason to be excited for a Sinister Six movie. Green Goblin and Electro look totally different, and while the original costumes from the comics probably look hokey to the majority of mainstream movie goers, that's what they look like to any of us who have been reading the comics for years. Why bother using these characters if they're going to change them so drastically?
Because what they look like is the least important thing that defines a character. Who says they were changed drastically? All we know is that they originate from OsCorp. This is obviously accurate for Goblin, and Electro's origin frankly doesn't matter, so what exactly do we know about them that changes them drastically?