Agreed. Wyll's quest is probably one of the most incoherent, despite (or because of?) having multiple interesting things they could be doing with the character.
When I first encountered Wyll, I thought he was a bit bland. But then when I took him to Karlach, and he was torn and genuinely debating whether to kill her simply because he didn't want to acknowledge that Mizora had duped him, I thought this was setting him up for a really interesting character arc about realizing that his black and white "I'm the hero" attitude was wrong, and that Mizora had him doing things that did a lot more harm than he first thought, even if she technically obeyed the letter of their contract. I expected this to get even worse after Wyll defied Mizora -- surely she'd retaliate by abusing those loopholes even further.
I also thought the conflict between Wyll and his dad might have been more interesting. Instead, they made it so that Wyll was completely in the right, a squeaky-clean hero, and wasn't even angry at his dad for kicking him out. I honestly expected there to be something genuinely bad or at least questionable that Wyll had done, where Wyll was stuck in his "hero vs monsters" mindset but his dad had deeper wisdom that let him see that Wyll was setting himself up for worse things to come. But that wasn't there either.
To say nothing of the fact that Wyll becoming a devil had... no narrative impact? A few allusions, perhaps, but it certainly wasn't the focus at any point.
The Balduran quest drove me absolutely insane. It was Wyll's quest... supposedly. But the Emperor arguably got more character development. But no matter who's quest it was, the significance of "Balduran" to ANY of these characters was never established. Yes, I realize he's a historical figure to them, but just because he has name recognition doesn't mean the reveal has any narrative weight. If I'm watching a Captain America movie, it's still going to be jarring if a random anti-hero turns out to have been George Washington. (Also, if you do this quest before rescuing Wyll's dad, the conversation with him about his life choices has so much whiplash. I saw a version of the conversation that played out with Wyll's dad present, and that one made infinitely more sense, even if it was still too little, too late). Setting that aside, I couldn't help but notice how Ansur had absolutely nothing to say to Wyll. This quest was positioned like it would be a test of Wyll's character, about whether he was worthy as a hero, but Ansur just had no interest in him at all. Talking about Balduran ended up being a distraction from the guy who's character was supposed to be on display here, and I don't think this happened to any of the other companions.
Honestly, the one thing I liked most in Act 3 was Wyll volunteering to go with Karlach. It felt like the perfect bookend to that early scene I really liked between them, except that the middle of his story had nothing to do with it.
Aside from edits to the main story, Wyll's storyline is the one I want to see adjustments to the most. My main votes are "Please reconsider the fact that we can currently do the Ansur quest BEFORE rescuing Wyll's dad (resulting in some very weird pacing)" and "Can Wyll's final quest actually be about WYLL, please?"