Why Spider-Man 3 diden´t work with 3 villain? 2 reasons.
1. They all were MAIN villain. Well this is big problem. It´s always better to have 1 main villain and other support villains than all big villains.
Big villain(main villain) needs more room, story and focus.
Green Goblin - Best friend who wants his revenge
Sandman - Guy who killed Uncle Ben
Venom - Guy who wants his revenge
Green Goblin and Venom are both biggest Spider-Man villain. Sandman however was main villain who had 3 fight scene, more focus on him.
2hr movie, 3 main villain = FAIL
2. Those villains were created too fast.
Green Goblin from Green serium
Sandman by accident
Venom by accident(at right place at right time)
Clearly lazy writing. If we have story like in TASM that Oscorp creates Villains, it´s more believable.
Why 3 villain will work in The Amazing Spider-Man 2?
First, Marc Webb and Writers told so many time that Electro is main villain. Rhino is very small part like Proto-Goblin. This worked in Dark Knight and can work in The Amazing Spider-Man 2.
TASM 2 and TDK
Aleksei Sytsevich = Scarecrow(both at start)
Electro = Joker(main villain)
Rhino = Lau(middle)
Proto-Goblin = Two-Face(end)
Movie begins. Batman beats Scarecrow, Spider-Man beats Aleksei.
Main villain, focus is Joker/Electro
Then we have another fight scene against support villain like Lau in Hong Kong and Spider-Man against Rhino.
Before the end Batman beats Joker, Spider-Man beats Electro.
Final scene Batman meets Two-Face, Spider-Man meets Green Goblin.
Spider-Man 3 - 3 main villain
Dark Knight - 1 main villain, 2 support villain
The Amazing Spider-Man 2 - 1 main villain, 2 support villain