Like Petra nanoseconds after learning about RbD went to go kill him, and she really likes Subaru (I get she had arc 4 Subaru influencing her a bit but she still went through with it of her own accord because she can choose to ignore him).
Literally all of Arc 9 comes from the fact that Al knew that Subaru could have stopped Priscilla's death, this might have been the smartest play that she could have made.
Now to get this out of the way I'm not implying that Goblin Slayer is better written or a better story than Frieren, just that the "bad guys" in it (the goblins) are generally far better written than the demons as a race.
The reason why I believe this is due mainly to the presentation of how both races are intrinsically "evil" or at least harmful to humans. To start off I'll talk about the demons and why I do not like the way that they are shown to us the audience.
From the start Demon's are described by Frieren herself as inherently animalistic, only using words as a way to get what they desire. What confuses me however is the logistics behind this. Demons in Frieren supposedly evolved to be able to mimic human behavior in order to hunt them more effectively the main question though is simply "why?"
This apparently is answered as it just "they are evil and want to kill humans" but there is no evolutionary purpose for this. They are almost never seen to eat other human's for food, they don't even seem to enjoy it for the most part it's just they do kill them. But why? Like why are they going out to hunt the most dangerous race in the world aside from themselves in order to kill them for literally no reason when it's actively harming their own survival. Even pure evil characters in stories need a reason even if it's no necessarily a good one otherwise it just comes across as a tad lazy. Like the best example is the Alien from The Alien.
It fundamentally hates humans and other forms of life but it attacks them as well, because it wants to reproduce, there is a reason that drives a natural hatred that as opposed to what the demons in Frieren just have for literally no reason. Well then people ask "So what's the big deal? They're monsters so they don't need a real reason." But another issue is that the author seems to want their cake and eat it too.
Demons despite only learning speech due to the need to trick humans but yet they are seen with several human and sapient traits even when there is no reason to actually use them. Demons have a social hierarchy that is completely irrelevant to hunting humans. They have individual traits and wants and desires that are fundamentally sapient despite being described as nothing more than animals that should be pest control.
This is the core problem as if we had a scene that showed when no humans are around to mimic they simply just walk around emotionless then it would not only be a good moment of horror but also a commentary on how different they are. But we don't in fact we have the opposite where we have Demons using self introspection despite seemingly having no morality (which isn't even evil it's just a lack of something so it still doesn't explain why they wish to kill humans as I doubt all sociopaths wish to do this secretly either).
This contradiction between being seen as animals or pure evil vs what the author wastes time to show us that maybe that it's not all like that before going back to a SURPRISE they actually are all still evil brings up the center piece of this side of the argument. Macht.
Macht especially should not be in this story.
Macht as character while interesting should not be in the story that the author wants to tell as he obeys all the ideas and rules that the story wants Frieren to follow and yet he never gets to change unlike her simply due to his race. This unintentionally ends up causing a "Tolkeins Ork's" problem where he is only denied his reward from the themes of the story solely due to his race.
To sum it up demons feel like they have no in universe reason to kill humans for evolutionary purposes to counter intuitive points in each demon having a distinct personality and other smaller instances which in turn gives the appearance of something controlling their actions to make them behave this way. That being the writer.
Contrarily the goblins.
The goblins are defined by envy. Goblins themselves are explicitly envious of everything around them, self-centered and prideful each goblin is fundamentally almost the exact same. Goblins in the story lack the power to make anything so they take and take from others. Now this is bad but it is also for a purpose, even if it's one that is counter intuitive to humans.
Goblins need people so they can eat, reproduce and gain enjoyment. Their very existence is opposed to other races which while sad also makes sense. They act in self-interest and are a wide-spread problem around the world. No goblin is that different from another because their way of life basically forces them to be. They unlike the demons in Frieren also actually are created by an unknown force of Chaos to be like this and make them be this way as well.
They are simple villain in contrast to the Demons whom are actually too nuanced for the story and point the author is trying to tell. The Tolkein problem is actually one I don't mind too much it's just one that becomes harder to read when the author gives separate information based on how demons work and what they actually do in the story that creates a sense of me not knowing what they are meant to represent in the work.
I hope I worded this correctly, I'm not a professional writer or anything and this is all just my opinion. I also have not caught up on Frieren and haven't been for a while so some information might be wrong or outdated but I hope I made my point clearly.