Fair enough, but keep in mind that the birthday thing is not at all my reasoning. I quoted the sources from where it was from, to give food for thought, and it wasn't the reasoning I used. My main train of thought is that they teased Norman Osborn's health in the first movie, and now they're bringing in Harry Osborn. It just seems like Green Goblin is the natural choice, and I still feel like Gwen is going to die (I highly doubt that a corny love triangle is the sole reason to bring Mary Jane in, which again, means Green Goblin is more likely for me.
I think the inclusion of the Lizard was a little bit because of the fact that Sam Raimi's movies wanted to include the Lizard as a villain (I know the actor for Curt Connors was keen) but we know what happened there, and I'm sure many fans were disappointed that the Lizard avenue seemed to get cut.
Having Lizard also fits in with the story they've crafted, because Curt Connors serves a good starting point for cross-species genetics and such. I'm guessing Marc Webb also had interest in doing the Lizard because the villain was never done in Ultimate Spider-Man, only shown in a flashback. The Lizard is more popular than you think
I like how they stuck to the first ever Lizard plot in issue 6 of The Amazing Spider-Man comics.
Then for some fun trivia, the Lizard was also the first villain to appear in The Animated Series.
I agree with your assessment of the Symbiote and Harry, I loved that whole story-line with Eddie Brock and the cancer-cure in Ultimate. It was fantastic.
I'm not completely sure if I want three films for the Symbiote story, but at the least I want a full movie dedicated to Venom and the Symbiote plot-line.
Thank you for reading, it's fun to discuss this with fans!
You've given me a fair bit to think about, and I'm glad the article brought discussion.