Having a worrying wife and son sure makes him an amazing
villain...
Seriously here, a villain needs to have a good motivation, personality and must be somewhat relatable with the audience to be an effective villain.
Lizard has none of those.
No motivation, he hisses.
No personality, he hisses.
He isn't even relatable by the audience unless you're a big hissing guy.
The only thing that makes Lizard appealing is his human counterpart, Connors, which isn't a
villain here, is he? If he wasn't tied to a person who is so close to the hero, he would immediatly drop to a C\D grade villain.
Also, from the general audience PoV, things like aliens and monsters instantly make a movie worse. Pop culture now instantly rejects genres that include those type of universes all of sudden.
I've explained this before:
A alien movie genre works for people because they're expecting to see aliens. They know what to expect. If you throw monsters or aliens all of sudden to people who are unfamiliar with the superhero universe, they will certainly go "Wtf?". Venom is a big example of this. He is a big breach in the before stablished universe of Spiderman because he comes from space, while everything that happened before was human conditioned, by science.
Lizard is another breach because, while you're still using science in his case, you're doing the Full Monty with him. You're turning him into a full science engineered monster. No human qualities are left for him.
While some stuff works in comics, it doesn't necessarily work well in movies. People forget about this. I certainly laughed when some people cried when they didn't get a giant man in a pink suit with a ridiculous hat in Fantastic Four 2. Their whole movie franchise is a big joke anyway, maybe that would had worked.
Anyway, concluding here, I'm not saying that I dislike Lizard. I actually love him in the comics and the games. As a main plot for an hour and a half or more of a movie, I have serious doubts tho. He doesn't strike me as something people want to see for a whole movie. If he is to get attention in a movie, we need a new villain to go with him. It needs to be done cleaverly or else it can seriously blow up in people's faces. I somehow doubt Raimi can handle more than one villain, after the ****fest that was the third movie.