I don't know what Hydaelyn has to do with the Scions, and I can't really contradict something you claim to have seen, but I'm pretty sure the vast majority of people were either neutral or outright hated the Ascians back then, effectively because there was nothing to like about them. They were pointless, shadowy figures with no background or defined purpose who more or less showed up at the end of any given story to do a bit of moustache-twirling and then depart stage right with no real impact or consequence on the actual plot, to the point I remember one of the most frequent sentiments expressed during the reaction to ShB was "I can't believe they made me care about the Ascians" lol. As for Hydaelyn herself, I mean, I think that's a valid take? As much as people around here like to ignore it, there have been hints dropped here and there about how she may not have been all that she seems, and I think what she did to Minfilia merits a lot of questioning even as they painted her as being okay with it (Argos bearing some odd resemblance to her is one of the things that weirded me out the most to be honest, and I never even like Minfilia that much.) And as for prior to that, well, people theorise, and the big Good being the big Bad is certainly a trope, and Hydaelyn had a certain vagueness about her nature that could invite that speculation, I guess.
It's not really anything to do with the writing giving poor reasons as to them tagging them along as it is outright ignoring the fact the characters are tired and could do with being left alone for a while, especially in a new set of quests that highlights new beginnings. I don't know if specifying any amount of time had passed would have done much to make a difference; for most feeling weary with the characters, I think the break needed to be for a while in our time, lol, and not something simply to be shown by the writers. The frustration was more a matter of the characters having outstayed their welcome than just being annoyed with the plot contradicting itself - expecting or hoping for a reprieve and then not actually having any real break from them.