AC97
I mean you can’t have it both ways, she can’t be both a useless waste whose inclusion would be tone-deaf (and only in a meta sense, the characters obviously don’t feel that way in-story) while also being a player whose lack of appearance is a criticism that reflects poorly on her, since she’s apparently supposed to show up to give Luna the forgiveness she already unquestioningly gave her in episode 2 of the series.
How is she even supposed to win here? Celestia shows up, you say that it’s tone-deaf, and she regurgitates the same thing she already said to Luna because I guess she just needed to hear it twice?
Yep. Again, the S5 episode is more about Luna forgiving herself, her friends helping her through it, the ones she wronged most recently, not Celestia, who, to repeat, forgave her instantly in the series premiere.
Maybe the unpopular opinion is feeling like the episode wasn’t necessarily lesser without Celestia there, even though this was at least in part because of how packed in the episode was from a meta standpoint; you can argue that maybe the episode would’ve benefitted by being a two-parter, in much the same way Keep Calm and Flutter On probably would’ve, or MMC.
A “bad reason” is exactly what Luna had as well:
Ponies are sleeping during my night → cause Eternal night, turn evil when my sister asks me to lower it
I really hope that’s not considered a sensible reaction to envy.
Luna tends to get more leeway in the fandom at large because a larger majority of people like her, therefore they’re more inclined to give her the benefit of the doubt in developed headcanons and such. Yes, you do get a building block or two more than Starlight did, in how her dynamic with Celestia is, but it’s still the case that at face value, it’s astronomically petty (pun intended). You can also say the same about Trixie, and how Twilight didn’t even try to do anything to her.
Honestly, it’s been a recurring thing for me that I think it’s potentially easier to get the mindsets of Celestia and Cadance, than it is for Luna, because I can’t help but think her characterization can be a little… muddy at times… maybe it’s just me.