I've got jasmine on my deck. It was a gift to my wife. It's a pain in the ass to keep alive, but I do it because I'm fond of the jasmine. Does not mean I relate to the jasmine. Doctor Manhattan has a human habit. He's clearly not one of us, though. Given the choice between helping humans or hurting humans he'll help because he's not malevolent... but he's got no skin in the game. That's one of the allusions Moore and Gibbons are making about power - the more of it you have, the less the little people matter to you. It's something Moore didn't feel with Swamp Thing. Swamp Thing is very much not omnipotent. As super powers go, he's basically a more durable version of Bigfoot. He's also barely interested in protecting humans - he mostly cares about nature. Moore makes a point with Swamp Thing that if Swamp Thing weren't there, "bad things would happen" but bad things happen anyway. With Doctor Manhattan not there, the world teeters towards armageddon.
I think Doctor Manhattan, in some ways, represents nuclear weaponry. A new thing in the world, with more power than we really know what to do with.
I've always wondered why Jon chose to make his body so un-human - surely he could have done it differently if he wished? Maybe just a literary device.
In some ways, yes. In other ways, no. They definitely talk about having Dr. Manhattan the same way we talked about having "The Bomb" prior to 1949. However, there's no "balance of power" involved in Dr. Manhattan to shape history from 1949 until 1986, and most of the World's history was shaped by that. With only one Dr. Manhattan, he means a lot more than nuclear weaponry. I don't think Dr. Manhattan chose to make his body un-human - after all, he spent months painstakingly reassembling it from the aether. I think he got "close enough" and stopped. Dr. Manhattan, after all, drifts further and further away from humanity. "Brilliant blue skin and no pupils in his eyes" is only foreshadowing.
In some ways quite explicitly! I think ... why would he make it human? He's not human anymore and doesn't attach any special significance to the word human. If anything I think the fact that his body is still recognizably that of man is a literary device that Moore needed to have him interacting with other people semi-normally.I've always wondered why Jon chose to make his body so un-human - surely he could have done it differently if he wished? Maybe just a literary device.