Brilliantly said. This was actually the main reason I think Galaxy 1 is better than 2, it's celestial backdrops and the slightly more poignant vibe of the music gave it more emotive depth than the blue skies and lighter tunes of 2.
That's it! That's exactly it! I was trying to figure out why Galaxy 2 felt unfulfilling and uncharismatic, now I believe you've put the finger on it - it couldn't let you enjoy the wonders of space depths. At times, even the first one took me out of the illusion - especially that dreadful Toy Time Galaxy. And there were times I could feel the emotive depth coming back to me in Galaxy 2, namely in the Cosmic Cove section.
Having actually built upon Rosalina's backstory in the first one helped a great deal. And I believe that's why she's a fan favorite in the Mario pantheon. The second one did push aside anything remnant of a story, it actually shipped you right into the platforming section without making you feel the excitement of running around spherical worlds and see the stars get lost into the Milky Way.