See, I had no problem with multiple villains, I just think they did it wrong. Seirously, Venom should never have even appeared in the movie. You had too much going on. I think what would have worked better would have been to have had Dr. Octopus come back, since he's already established, keep him behind the scenes for most of the movie, and focus on the Sandman and New Goblin. Then as you realize Dr. Octopus is pulling all the strings from the shadows have Harry become Spidey's ally for the finale. I think a film focusing on the Lizard and Venom, with Black Cat as a new ally would have been a better match.
Green Goblin, Dr. Octopus, Venom, and Sandman have all gotten their spotlight, the only real major villains left are Electro and the Lizard.
I think a great way to include more crowd-pleasing villains would be to have them involved in less-plot intensive mini-fights. Maybe open the film with a brawl against the Rhino, who we don't see again. Instead of a bank robber taking off with an armored truck as a distraction in the middle of the film, have the Vulture pop up and get taken care of quickly. Or maybe a montage to show how busy Spidey's been with snippets of battles between him and Shocker, Scorpion, White Rabbit, whoever... This would of course also lead to more TOYS!!!