What stops me from finishing the game a second time

With the Christmas vibe in the air, I felt like playing the game again. I had one fairly early save from my second full playthrough attempt.
While playing I found all the things that I loved the first time around. I was taking much more time to explore the castle, look at every little detail they put here and there. But after three short sessions I kind of gave up again. I remembered why my playthrough was unfinished.

The two main reasons for this are as follow :

1) I feel like the game lacks polish.
Yes, the castle is very detailed and full of little surprises, but that's not enough after a few hours. First of, I get tired of hearing the same lines of dialogue, the magical instruments playing the same exact song 24/7, my character reminding me to look for gobestones in a location where I already found them. I feel like the magic is lost very early on, as the dynamic events keep repeating themselves over and over (the angry armor destroying the humming armor, the ghost being chased by his wife, Peeves, ...) The broom controls are also lacking (looking up or down should be an option), the controls to summon the broom, and not being able to fly over the highest tower or to land on the roof is so frustrating.
I think the devs did a great job for a studio's first open world game, but another year for polishing and quality of life changes would have been a good idea. Lots of things could be patched in, and if the Definitive Edition/Director's cut is coming out, I hope they implement a few things.

2) This is my main issue: I can't stand the voice acting, characters and dialogues.
While the game lets you walk a darker path and use unforgivable curses, the story and acting feel completely dissonant with that. Of course you shouldn't sound like an evil psychopath, but I feel like all the dialogues are too cute and naive. Everyone in the game is so kind and helpful, it's like they're in a cult. And when a character is remotely evil, their voice actors bring no subtlety to their lines. It feels like you're watching an episode of Peppa Pig.
The only character that's well written for me is Sebastian, but in any other game his arc would be considered better than average, or good. It shouldn't be the highlight of the game.
While replaying the game I found myself skipping every single piece of dialogue as it just breaks my immersion. Even Simon Pegg, who's an actor I love, can't change the fact that his character is terribly written. I see they try to make him ridiculous and despicable but I don't find myself chuckling even once, I just cringe whenever I see him.
And I just realised now that they had Luke Youngblood, Lee Jordan's actor from the films, to play some parts in this. While I think this is great, I found out because I was looking at who voiced the most irritating character in the whole game! Why make grown men play teenagers when it makes them sound so weird and disturbing? This is such a missed opportunity.
Everett, to me, is one of the most unsufferable characters, alongside Amit and Phineas. But Poppy, Natsai and many others are not great either. The gap in the character writing between this and the books, or even the films, is too big for me to ignore. The world of Harry Potter is fascinating, but it wouldn't have been as successful without its characters and stories.

Does anyone here feel the same way or am I just nitpicking ?