A lot of things goes against Rosalina's canonical abilities in games like Mario Party and 3D World (and any Mario spin-offs, really), especially if you consider the fact that despite her being fearless, forming force fields, and aviation, she still gets "scared", harmed and falls. I don't have a problem with that since we know she would be too strong (physically and mentally) for these games, and since her going all out would render the game useless, the developers had to tone her down.
It would be nice to have some sort of reasoning to why, but instead, we get the implication that she's holding back. I like to think of these games as systems, with Rosalina knowing she can very well surpass them, but still choose to abide by it 'cause she's a good woman and not a cheater.
With that aside, Rosalina showing up in these games isn't that bad, and it's a normal thing considering she was made a staple years ago, thanks to her popularity. So yeah, it'd be strange to consider Rosalina, a part of the Mario main cast and mascot (who made a spot in Smash to represent Mario), an essential character to the lore and universe, and additionally, a well made character with tons of depths, to not be in a spin-off game with the Mario cast. I do admit, I miss her portrayal in Galaxy, and it has been so long since she was in a game like that. I also miss the Lumas.