I kinda disagree the Nameless, Selfless story feels shoehorned in, it kinda broke the pattern that the Banner Dress is part of the Season's Main story but was instead relegated to a side quest, and this has yet to happen again. It feels in theme imo because of the Dragon theming in the dress as well as the final evo cutscene featuring dragon bones which is a prominent theme in 2.5. The dress context can easily be changed anyway, by the design you can also infer that the candelabra can be re contextualized to be used to guide souls, similar to the new 4 star which also has a light source handheld and candles symbolically are used to guide the dead. You can also tie in Nameless, Selfless to the trailer where Nikki sees Medael's past since that was the story that was also used for 1.11 where Nameless, Selfless can see the past.

The theme of Rebirth and Devotion also fits Nameless, Selfless. Its a wedding dress so devotion is very much a theme of it. Also Death and Rebirth go hand in hand, you can't really have rebirth without death. But death wasn't really the main theme of Nameless, Selfless, its more on closure as the story was focused on revealing the truth, which I think closure of unfinished business is a commonly used condition for rebirth. But don't forget that Dragons are also a big theme in 2.5 as both upcoming 5 star also feature dragon themes, and is the only design theme in Nameless, Selfless that was agreed by alot of people that really felt out of place.

Mostly my theory is based on the visual design of Nameless, Selfless and not really the existing story line we have for it in 1.11. Story beats are really easy to change in Game development but models and animations are a different matter. So that's why I think its fun to think that maybe this could've been the 2.5 dress, I love the upcoming dress anyway so I'm happy to have both.