Rosalina doesn't sound too high pitched or girly. She screams and yelps a little in MK8 and 3D World because she's doing much more exciting things than she normally gets to do. She doesn't have to stay monotone when she's jumping off a freakin' waterfall with a big adorable water dinosaur...thing, or driving around on an awesome quad bike, against gravity, at an electronic dance party. This is part of her "agency" that I talked about. Rosalina is, in general, very serious, monotone, reserved, and gives off a lonely feeling (specifically her eyes) despite the near constant company of her Luma children. However, she has things that CAN make her scream and yelp with glee, and make her smile and laugh. Just like how she has things that make her quiet, or assert her authority, or things that can make her feel down, or even cry with sorrow. The various games she's been in have established a wide array of clear beliefs, likes, dislikes, etc, that Rosalina has. This makes her feel much more real, and human (while still retaining those fantastical elements to her, such as her immortality and god-tier status in the Mario universe). You're basically saying that Rosalina SHOULD be a one dimensional character. But one dimensional characters are a bad thing the vast majority of the time.
Daisy does not have these qualities at all. She is one dimensional. And Peach mostly is too (and it doesn't help her case that the one game she was the sole star of made her goal to chase after a vibrator - no, I'm not kidding, the Vibe Scepter is literally a vibrator. That's not me being dirty minded. It's very clear cut and dry that thing is a pleasure toy, or a metaphor for one at least). I will give Peach that she is entertaining in the RPGs (not a deep or inspiring character, just funny and sometimes a bad***).
And design-wise, Daisy and Peach share way more similarities than Rosalina does to either of them, even after Daisy's redesign - she still has a very similar build, she still has a near identical set of clothes and accessories to Peach, she has similarly petite "assets" to Peach (compared to Rosalina's more matured "assets"), she is still symmetrical in design like Peach is, she is still "cute girl" in terms of the mood her overall design gives off - as the AV Club put it "Peach and Daisy are girls. Rosalina is a woman".
The red glow in that screenshot is a different colour to the one in Luma Shot, and Rosalina is performing Gravitational Pull. Rosalina cannot perform Luma Shot and Gravitational Pull at the same time.
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I think I ship this. :3