Rosalina hated it here.
Three reasons why:
One: it was incredibly dangerous. The floors and walls and platforms come and go at random and sometimes inopportune times. The way the safe spaces constantly moved around made her feel equal parts sick and scared for her life. And speaking of life: it could not thrive here. There were no naturally occurring food or water sources, no guaranteed safe spots to build a home, and no indigenous species. And - she couldn't stress this enough - it was so dangerous. Why anyone would want to come here was beyond her. How Mario managed to make it through here without dying a million times was also beyond her.
Two: it was pretty ugly. The shifting remains of what had to be castles or temples of some kind were okay to look at, but that was where it ended. The entire landscape - if you could call it that - was dominated by the muddy yellowish-green sky. The swirling mass of natural gases in the atmosphere was dizzying. It hurt Rosalina's head to look at it for too long. The sky was unappealing, unattractive and unorderly in every sense of the word.
Three: how silent it was. Since no one lived here, the whole galaxy was utterly devoid of life. The only thing left to fill it was a crushing silence. A person's footsteps on the stone would echo throughout the air, with nothing to impede it. Now, Rosalina normally liked the quiet, but not this kind of quiet. Not the eerie kind that made goosebumps sprout up on her skin. Not the kind of quiet that felt almost dangerous, somehow.
Yes, Rosalina certainly hated it here.
It was never on her travel itinerary; the only reason she was even here in the first place was because the Lumas wanted to go to the Cloudy Court Galaxy to see the Wind Show, but in order to make it in time, she took the Comet Observatory through Matter Splatter as a shortcut.
She would never come here otherwise. There was nothing for her here.