It's like i was saying in the Bane thread, the problem with lizard is that...he just wasn't human enough (or that he was too human) Comic books are still films with humans, and villains tend to be human characters who can emote and establish a connection with the audience no matter what...either that or the villain is nameless and elemental. He's a monster, an effect that destroys everything in it's path that evokes fear....you can't get that when your character has a voice and a character but is hidden in a cgi f***fest that is the lizard, it takes you out of it. This isn't WETA and Lizard is no gollum, should have done Andy Serkis to do Lizard and get a proper performance out of it, but it's all half assed, and no one can get into the character because it's just a walking talking cgi effect.
It's why i don't think Thanos would work as a main villain in an Avengers film, because they need a proper real life actor to go out there and breathe and live his role, they need him to emote and act...if it's some cgi effect with some guy doing a voice, then it will never work as a great villain like it does in the comics.
So yeah...the human element very very important in films.