The only benefit of a doubt I can give them here is the fact that she was a late addition, and the engine plotline was added very late in her development. So it might be more of a "well, we never did any content that was cut simply because we didn't have enough time to properly flesh out the alternatives". Although that just makes me think they should've pushed the game further back, instead of giving us an Act III that is very unpolished in a lot of aspects, and the weakest part of the game. It feels like Act I and II were done with a lot of care for major inconsistencies and plotholes, and III just was "lets wrap this up quickly".
The thing is though, that she's not really a late addition. She's been in the game pretty much from the beginning of EA. They'd at least been planning on making her a companion for a long time. Yet her story has been entirely neglected.
I think this just makes it even more likely that I'm never gonna complete this game. Larian made a good game, but it's really not that good. Larian has a lot of passion and ambition, but seems to me they're also like a bunch of disorganised teenagers wanting to shove everything in that they can with no regard to whether it will fit or make sense. This game is... just another crpg. It's got its own unique strengths, but it doesn't deserve the love and praise it's getting, not by a long shot. Larian are fine devs but just that, they're fine. Which is okay, we shouldn't demand every game be the best thing ever. It's fine to be fine.