Somehow in my many viewings of The Wrong Jedi I have never noticed Padme’s costume. It is a good costume.
(To be fair, the episode’s just a little overwhelming on the emotion front, so a bit (a lot) of oversight is understandable.)
It’s formal, it’s mature, it has a lot of ceremony, but the overall silhouette is a streamlining of an AotC costume: Padme’s packing dress. The skirt and sleeves aren’t as full, the collar is a tight stand, the colouring is sombre reflecting the situation, and embellishment is stripped right back to texture and the belt and added formal tippet (perhaps an indicator of her role in Ahsoka’s trial).
It’s a move away from the slightly period look in the AotC grey (the button sleeve detailing – a rarity in SW and seen maybe three or four times – is very pointed), towards something that bit more Star Wars. This evolution shows that she has clearly grown and advanced since AotC, and her wardrobe with her, but she is still young and still feminine even whilst she is a force to be reckoned with. This look sits comfortably with where she is, and the fashions shown to be favoured by her peers and colleagues, most notably Mon Mothma and Bail Organa. It’s a throw forward to the senate under the Empire, Rebellion leaders, reflecting the simplicity that we saw from Leia in ANH whilst displaying the prequel era opulence in understated way.
The lack of overt-grandeur may also indicate a person scaling back to show sympathy for the people suffering in the war, or perhaps necessary cutbacks in trade expenses, budgeting, self-imposed rationing. This, again, would throw forward to the utilitarian-by-necessity of the Original trilogy, and reflects shifts in fashion during WW2 rationing. Parallels could also be found in the shifts from the fashions of the Edwardian Golden Summer – the bright, grand years of the Western upper and middle classes before the break-out of WWI – to the shift to the sombre simplicity through the War. Padme’s AotC gown is more of a fantasy-by-way-of-pseudo-victoriana, but that echoing and shortening of silhouettes, maintenance of fashions in those upper classes by different means. In solidarity and in pragmatism. Silks replaced by wools. For Padme, velvet with a subdued jacquard.
Costumes like these, costumes that made sense for the character and the escalating situation, were what were sorely needed in RotS. Pregnant or not, the next development of this look would have been better than just throwing bolts of fabric at Padme, which it sometimes feels like they did. Considering how underserved Padme was in that film, lending her support and structure in her costumes would have at least been a step towards giving her any sort of standing, and would have particularly worked well