The death of millions would be the necessary galvanizing force to make people jump to their feet screaming for blood.
And what would they do, exactly? How do you fight a god?
Dr. Manhattan was so associated with America that worldwide genocide on his part would likely just turn the other countries even further against the US, not unite the world.
Yep. And of course it wasn't just that the squid was perceived to be extraterrestrial; it produced a psychic resonance so that every person on earth felt the deaths in New York and had no choice but to turn their backs on violence. To say nothing of the madness and manifest destiny themes weaving through the book that tie directly to the squid.
One of the problems Watchmen has as a story is that it doesn't work. It's too aspirational (I think the book is only cynical on its surface). I'm talking about the book, not the film. We've seen Hiroshima and Nagasaki. We saw those planes fly into the World Trade Center. We saw the Nazi war engine ... and half the world joined them. The Russians helped us fight that evil and we turned around and stabbed them in the back. It has to be an extraordinary event to result in world peace, and Dr Manhattan confirming the fears and suspicions about masked heroes doesn't achieve that, especially because he's an American weapon, used for American imperialism. If he attacks his masters, the rest of the world sees that as justice. If he attacks the rest of the world, well, he's been doing that for decades anyway.
It makes no sense. And if Ozymandias wants to pin everything on Dr Manhattan, what's the point of engineering his exile to Mars?! Ozymandias can't pull off the frame if Dr Manhattan isn't here anymore. World peace doesn't happen. He can't possibly know Laurie is going to talk Dr Manhattan out of his exile, and if he did know that, why bother conspiring to send him there anyway?
They took out a piece of the puzzle and didn't bother to replace it with one that had the same shape, because they were more interested in Dave Gibbons than Alan Moore. And that's fine. That's one way to appreciate the book. Many people will like this film. Many people will be so happy to see Laurie walking around in rubber that they won't care that she can jump several stories without a scratch or throw people across a room and through a wall.
And hey, Snyder could have given Dr Manhattan underwear throughout, making a lot of people a lot more comfortable but missing the point of his nudity. He got a lot of it right and I'm not going to discredit that. Right now I think the film is a bit of a curate's egg, a noble failure. That's not necessarily a bad thing, and I look forward to seeing it again with a real audience, seeing how it plays and seeing whether my reaction changes.
I don't want to come across as too negative, just because I'm focusing on things I find important. I recognize other people don't necessarily watch movies the way I do, and there is certainly a lot to get excited about here.