What the Hell was it? He spoke with Laurie about the lack of a need for the existence of life and development. He pointed out that Mars would have been no more perfect with the addition of a shopping mall or oil pipeline. As a practical matter, he had no need of it for transportation, he teleported to Mars in an instant. He had no need of oxygen or thermal protection and provided those to Laurie when she visited and protected her when the device crumbled.
So . . . is it just something cool for the viewer/reader to look at? Or what?
However, he failed to design away the primary resonant structural frequency modes in response to a potential forcing function. Color me somewhat unimpressed with this “Dr. Manhattan” and his supposed omnipotence. So he can flit from Earth to the surface of another planet in a microsecond. So he can reconstruct himself from component atoms. So he has a giant blue schlong that has every man in the audience cringing in a combination of shame and envy. But he can’t build a structure that will withstand dynamics from even a mild impact. Weak.
If I remember right, his father was a watchmaker and though Jon initially planned on doing the same, after the bomb is dropped on Hiroshima the father insists that Jon study nuclear physics. It’s been awhile since I read it, but I think the father does something dramatic like throw all Jon’s watchmaking equipment in the garbage or out the window. So I thought that the Mars palace was also an attempt to get back to the life that was destroyed by atomic physics in more ways than one.
Naah – he knew it was going to shatter when Silk Spectre threw her perfume bottle at it/struck it with her fists (depending on whether book or movie) and that it would make an appropriately dramatic scene. It’s not clear that he wanted this to happen, but, being Doctor Manhatan, of cours, he knew.
Besides, he can remake it with almost no effort in the blink of an eye. Saying that it’s not built strong enough is like complaining about Klenexes for being disposable.
Dr. Manhattan is not presented as being omnipotent. Preventing a thermonuclear holocaust if both the US and USSR emptied their arsenals at the same time was explictly beyond his power.