The mere fact Raimi is listening to the silly 'too many villains' complaint is indicative that he hasn't identified what the actual problem with the movie was. It was the writing. Plain and simple.
It was too much unnecessary stuff they used to spend time. They focused too much on Peter and MJ's relationship(which was already established) and have Harry and her cooking, dancing, reading poetry and other useless things, instead of developing the villains, Spidey's double life and showing MJ as a partner in life, like she was in comics, talking to Peter about his battles and curing his wounds, being present, caring. A different writer would matter, though.
Just too much unnecessary things going on. Both the 90s cartoon and TSSM handled the symbiote story a lot better. They developed so many things (many more things than the movie) within 60/90 minutes, telling the symbiote saga and Peter's showdown with Venom.
Multiple villains doesn't automatically make a movie bad and having just one is not gonna automatically make it better. Batman and Robin still would have sucked even if Mr Freeze was the only villain, because of the bad take on the characters, the tone of the movie, all the cold puns, etc. If the story and direction is good. Movie is good. Regardless of the villain count.