Using this panel as an excuse to point out how freaking beautiful Thriller Bark is, but also...I think it's interesting that Moriah chooses to live this way.
There are certain aspects of Thriller Bark that can't be helped, like the foggy darkness of the Florian Triangle, and other things that seem part of Moriah’s base personality, as even in his younger years he seemed to have a flair for the gothic. But I do think it’s significant Moriah chose to turn his island-sized ship into a giant graveyard.
Much of Thriller Bark is about loss and how people respond to it. Compare how Moriah treats his dead to Brook. After his loss to Kaido he isolates himself, lets himself go, outsources all the hard work of being Pirate King to zombies he doesn't give two shits about and who don’t feel pain to avoid being hurt again.
Brook isn't able to bury his crew until after he gets his shadow back, but he does the best with the resources he has, while honoring their last memory and wishes. He eagerly jumps at the chance to make new friends and find a new crew, because the simple joy of being alive is enough to sustain him through fifty years of horrible isolation.
Moriah is surrounded by a loyal followers, but he doesn't seem to spend any time with them. He never could bring himself to make meaningful connections again after enduring the loss of his first crew.
Both characters are haunted by the dead, quite literally surrounded by corpses on all sides, but despite those similar circumstances, their pain and loss take them on very different paths