BLOGGER'S NOTE: To avoid confusion, I'll be using "Maguire!Wicked" (and other similar terms) as a catch-all for the novels and "Universal!Wicked" for the stage musical and films.
I've always maintained that disliking a character in a work of fiction isn't necessarily a measure of the writing quality, and can happen simply because I don't agree with the character's actions or conduct. With Glinda, though, I find that both her Maguire and Universal iterations suffer from opposing issues, yet the effect they have on my perception of her is equivalent. Take Maguire!Glinda, for example. She's far from what I consider a "good" or "perfect" person—my mind immediately jumps to the one-too-many eyebrow-raising comments she makes in the novel's first half while writing this—but her arc of realizing there are more important things in life to worry about aside from social capital happens much earlier (Shiz-era early, in fact), and the maturity and newfound commitment she carries towards her studies in sorcery are genuinely compelling to see unfold; even the other characters are left surprised by this evolution. The issue lies in the fact that Glinda effectively vanishes from the rest of Maguire's novel after Elphaba leaves Shiz University, and what we do see of her in the second half of the story is told to us through quick vignettes or passing mentions by other characters.
Universal!Wicked, in contrast, gives Glinda plenty more material to work with, and in that regard, I would consider her a better "character" than her book counterpart. However, this new material casts her in an unmistakably negative light. It stands to reason, seeing how this story is a perspective flip for the so-called "Wicked Witch", that the "Good Witch" would have some skeletons in her closet, but having Glinda overlook the injustices in Oz until she couldn't ignore them any longer made for a weak arc. What's even weaker is how the movies try to justify this by framing Glinda as using her social status to compensate for her lack of magical talent.
While I understand this is likely commentary on the real world—commentary that Glinda herself addresses in "Popular"—the second movie now expects the audience to take her aspirations of becoming a sorceress seriously, when every time Glinda's interests are mentioned in Part One, it usually leads to a punchline: Morrible ripping into Glinda moments after gifting her a training wand, the extended bit of Glinda failing to transform Elphaba's nightgown during "Popular", and being rebuffed from examining the Grimmerie like she's some overcurious pet. There is only one scene that highlights Glinda's struggle with magic long before she ascends as the Good Witch, and that too ended up on Part One's chopping block. The only other scene is the childhood flashback, which parallels the one Elphaba had in Part One, but fails to garner any serious sympathy for the same reason I just described—one kid snarks about Glinda being unable to do real magic, only for the entire party to be distracted by a rainbow and not bring up the subject again.
I think it would've helped to actually see Glinda's limitations in her role as "Good Witch" beyond the songs she sings. Some deleted footage from the trailers implies that Glinda would've gone on an Eva Peron—style tour during "Thank Goodness", and I think that was an optimal opportunity to do one of two things: have there be glimpses of Glinda being unable to immediately charm her way out of certain situations, or depict the Ozians growing too worried from all the Witch propaganda to partake in her spirit-lifting. Additionally, while Morrible has covered up or exaggerated Elphaba's magical outbursts throughout the story, what if she tried to fake Glinda's so-called magic as well? It's implied the sorceress never even bothered to advance Glinda's studies once Elphaba went rogue, but what if she did try at some point during the timeskip, and Glinda was either so magically incompetent that Morrible was ready to give up on her, or that it was more important for Morrible and the Wizard to fuel the propaganda against Elphaba rather than actually try and build Glinda into being a genuine public hero? It could have been a great point of contention between reluctant teacher and hopeful student.
To be expanded!