So there's absolutely no way these two didn't have bigger roles in an earlier draft of BW, right? You're not gonna convince me that characters this intricately designed and mystical-looking with original Japanese names of, I shit you not,
Goddess of Love and Goddess of Peace were always intended to have 7 combined lines total across the entire duology with no battles. Assuming I'm right, what do you think the original plan was, and why was it cut down?
I imagine the original draft had significantly more detail planned for N's past rather than having it mostly at the end. A lot of the concept art, especially for N (shoutout to the brief time he was missing one of his mouth cheeks), was a lot more dark and serious. I imagine the pair would have showed up throughout the game to give insights to N; or at least show up alongside him during the back half of the game like the sages kinda did alongside Ghetsis.
To add to that, and taking into account hot much more darker N's original concept art looked, I could also see them being
spanners in the works of Ghetsis's plan. Pretty much given the role as N's caregivers & guardians, they would firsthand see Ghetsis's plan unfold as he manipulates N, but not being strong enough to stop him they sit back and watch, possibly doing their best to undo mental damages Ghetsis causes (though in secret as not to have Ghetsis remove them). However, when the player enters the picture, they would see them as potentially the one strong enough to free N and even thwart Ghetsis's plans. So, as
R_N said, they would appear every so often, giving tidbits of backstory about N, eventually asking the player to help save N from Ghetsis. And with that there would be plenty of opportunities where they could help the player whenever Team Plasma has or is about to show up, such as pointing the player in the right direction, helping them with a puzzle, and/or even healing their Pokemon and giving helpful items.
In addition to probably time restraints and simplifying the story where it become less darker thus N needed less soul saving, I could also see them running into a wall with what to do with their character in the later part of the story. Now an exciting idea would be Ghetsis figuring out what they were doing (possibly from one of the Sages) and after talking with the player the Shadow Triad appears around them, teleports them away, and part of the storming of Team Plasma castle would involve saving them (and in return that would give them the strength to confront both N and Ghetsis along with the player). However that would add a layer of complication to things where just having them appear to help the player & tell the rest of the story before the player's major battle with N would suffice. And in the end that's all they ever end of doing.
Another example:
the war in the past in the Lucario film.
<-- This one.
WHO. FOUGHT. WHO? AND WHY?
How can I care for a plot-relevant war if you don't know who fought and why they fought!?
Well look at the armor, it's obviously Team Green Version VS Team Red Version.
Joking aside, since the Pokemon films take place in their own location not in the games, there's no way to know the "sides" unless specifically told. But, in this case, and with the Kalos War, it doesn't matter.
How can you care about a plot-relevant war? You don't, cause it doesn't matter. It happened, it's over, it's just a plot point. What matters is specific characters who were affected by the war. You're meant to care about AZ who had their partner taken away from them only to be meaninglessly killed driving them into a mad depression... and then a mad hatred. You're meant to care about Lucario who he and his partner had to act fast to prevent their kingdom from being destroyed which ended up Lucario trapped for thousands of years in a crystal staff and his partner dying (and Lucario ensure why and holding resentment toward his partner until the truth is revealed).