Luma Warp is the special that dominated standard special, not Shooting Star Bit. The Rosalina boards, over more than a month of discussion, pretty much agreed to this. Even in the v1 discussion, no one talked about Power Luma Shot in a way that suggested "I'll use this in tournament"; every post about this move was always a hypothetical "it doesn't seem so bad". Dabuz vouching that it's just awful and should never be used was pretty convincing; in far fewer words than I'm about to use he's expressed that it's bad and shouldn't be picked.
As a Rosalina main, I've personally explored it a fair bit. Here's what I found. The priority and power is nice, but it's still something the opponent can beat unless you fully charge (and your opponent has to be a dummy to let you fully charge and then somehow hit). You lose complete control of Luma for the entire animation, and Luma projects out from Rosalina so slowly when you use this move that the area beyond your normal fsmash range cannot be effectively controlled with it wheras if you don't charge it so much that you won't hit you're generally better off just using fsmash in the first place to control that space (and random fsmashing isn't even good!). Approaching behind a slow moving projectile can be very useful in some match-ups and was a reason I kept suspecting the move had merit for a while, but in practice, I found I was always significantly better off if I desired that gameplay mode to use Floaty Star Bit + Luma Warp instead of Power Luma Shot + Shooting Star Bit since with the former I retain my full range of normal options whereas with the latter I am completely tying up one of my characters which is ridiculously limiting. Using Power Luma Shot made me ridiculously predictable; Luma loses almost all mobility, and that in a lot of ways is taking away half of my moveset. You simply cannot, if you pick this custom, project Luma beyond Rosalina's normal range effectively, and every time you hit the button for this move, you're basically simulating your 12.5 seconds of unhappy "Luma is dead" time with Luma still alive. Nothing Power Luma Shot offers begins to compensate for that kind of loss, and since Floaty Star Bit exists for your "chase a slow projectile" needs (and Floaty Star Bit is completely transcendent and actually does beat literally everything except reflectors), it's really hard to justify Power Luma Shot.
When I was playing opponents who didn't know what was going on, I was able to get some serious mileage out of the move since I could trick them into just running into it. Whenever I fought anyone who was a more competitive opponent, they would make me really regret picking the move every time without exception since they were smart enough not to get hit, they'd abuse that Luma was never going to move anywhere quickly in their spacing decisions, and if I used the move they'd aggressively bully the Rosalina who willingly locked her partner out from doing anything helpful for an extended period. In that sense, it was "useful" to troll weak players, but it was never, in any match-up, a tool that would enable Rosalina to win where she otherwise would lose. That's somewhat different from what you're saying @
ParanoidDrone
. I was the one who said that, as a Rosalina main, that it helps against players who lose to you already since it's often easy to trick weaker players into getting hit by stuff they shouldn't, not against characters who lose to you. I do not believe it's helpful against any characters.
The progression of sets also has to be understood for Rosalina...
Dabuz has said that he would use the following six sets in tournament: 2311, 2313, 2321, 2323, 2111, 2121.
Of those sets, 2311 and 2313 represent by far the most common opinion of Rosalina mains, and we've also as a group been pretty convinced up-1 vs up-2 is a very subjective preference choice so 2321 and 2323 deserve inclusion even if dabuz doesn't exist (he's just a great, credible source telling us we're right). The two default Star Bits sets are sets he alleges are useful in the Luigi and Olimar match-ups (since both of those have projectiles, no Guardian Luma variants are necessary). To be honest, as a player, I don't see it, but I don't think any of us are in a position to credibly tell the best Rosalina player by far that he is wrong about this. We have six sets that are in regardless.
That leaves us with four to fill. By far the most popular move not in those six necessary sets was Floaty Star Bit, and as a Rosalina main I'm entirely convinced it's the best one remaining (it's not just me either). Giving 2211 and 2221 at least was pretty common sense. From here we have two sets left. Many Rosalinas who are not very experienced with customs want Shooting Star Bit but are not comfortable giving up default Luma Shot. Locally I have had many custom inexperienced players ask for this set, and I'm almost entirely certain that's a common experience. 1311 will be picked at EVO even though, to be real, it's purely sub-optimal. It had to be included.
The last set was always going to be either 3311 or 2331. Honestly someone asked for 2331 in a way that implied he would pick it whereas no one did the same for 3311, and that was the biggest factor. As a player, I do believe 2331 is the better set. Even though the attack on Launch Star Attack is seriously crummy, it does add hitboxes to your up special. There are a huge number of possible gimp set-ups against a recovery that doesn't hit, and I would easily believe that even the poor hitboxes on Launch Star Attack could protect against at least some of them. The recovery distance nerf is pretty harsh, but Rosalina's recovery is still serviceable with Launch Star Attack (to be honest, the distance is pretty excessive with the other specials). She can also use it, in a very niche way, in juggle traps since it lets her cover areas she otherwise can't hit (or can drag people off the top!), even if it has substantial disadvantages. Lastly, as a matter of game theory, it seems like it might have some use in the Peach match-up if she holds a float just above your usmash range; it would let you actually punish her sliding in and out and dairing you. None of it is truly "solid", but there are quite a few reasons that Launch Star Attack might be selected, and the case is a lot more compelling than for Power Luma Shot which has been explored by several of us and written off at the same time.
In order to add Power Luma Shot sets, some of the above has to be removed. I mean, to be honest, I think changing sets at this point would be remarkably poor judgment regardless; the public discussion for this lasted for over a month so everyone had a lot of time to be heard, and TOs have already begun implementing these sets on their hardware so it's a big burden to just start changing sets. I'm sorry if this isn't satisfying to you, but we sought to give Rosalina her best set of overall options and in doing so included the sets that every Rosalina main who participated in the lengthy and public pre-release discussion was wanting to use. As a Rosalina main myself, I would really advise you to check out the 2211 and 2221 sets if you like the slow projectile thing; they'll really up your game while letting you go for the same kind of thing.
