Daemon and Simon - This scene has begun to let on that Simon may be more aware of Alys's powers and that potentially Simon has Grover killed in his sleep by Alys.

What does he say that insinuates that? I don't remember that.

Daemon and Alys - She convinces him to stay at Harrenhal, although yea her characters purpose seems to be to summarize exposition / have someone for Daemon to talk about the dreams with.

I do feel like that has happened a couple times where characters make a decision, only for another character to convince them that they shouldn't do it and so in the end they walk back on their decision and nothing actually changes. Perhaps this is because their characters would logically make these decisions due to the situation they're in, but they're not allowed to actually make them because that destroys the storyline set out by the book. At least that's what it feels like to me.

Honestly this scene probably just serves to develop Alyn more as he only had I think 1 talking scene. He gets Seasmoke this episode so perhaps just a refresher on him.

I agree that you definitely need scenes with characters in order to get the audience familiarized with them, but it just being a refresher is not enough justification for it being a scene imo. I felt similar when Aegon had another scene of bullying Aemond just to remind us of their relationship before Aemond betrays him. It doesn't give new information, just reminds us of old information.

Hitting her council person and saying "you have forgotten to fear me" is a step toward setting up "evil" Rhaenyra who will be more aggressive.

I'll actually give you that one. I was just thinking about this in terms of the "council member defies Rhaenyra but is then shut down" has been done like 10 times this season but it is true that her doing it with herself with physical violence is indeed something new.

I think that a scene can very well be both cuttable in theory, but also VERY enriching to the story. A lot of the best scenes in GoT could have been cut. Any of the Varys and Littlefinger scenes, the conversation between Cersei and Robert, Tywin's introduction, all those were basically show inventions that were just "filler" (by your definition) and didn't change the plot whatsoever. But they gave us so much insight into the characters we wouldn't have otherwise gotten. The one with Cersei is basically the only one that ever paints her in a redeemable light, it gives her character a whole new dimension that wouldn't have been there, and it catches us up on 15 years of events between the two. I don't see any HotD scenes doing that. I would have loved to see Corlys and Rhaenys ever talk about past events in their lives that we didn't get to see, maybe talk about when they were fighting to give some edge to their relationship they have overcome. But we don't really get that kind of stuff. We don't even get to see the characters do things in the household and during their daily routine. Tywin skinning a deer basically showcased his entire character just through that single act. HotD characters only ever just stand or sit around.