Your opinions are your own, but I do think Ameri is often not given credit where it's due.
For one, if there was no Ameri in the story, Iruma would *never* have stopped being a wallflower. He wanted only to keep his head down until Ameri was the first person to ever ask Iruma what *he* wanted out of his life. Nobody else did: not Clara, not Azz, Opera only asked if he wanted to return to the human world. But Iruma realizing he had no answer, and following her suggestion set him on the path of growth and development as she imparts the lesson of ambition into him.
This never would have happened without Ameri. But you don't have to take the text's word and my word for it, you can look to the author:
Editor: The scene where she realizes, “Maybe I’m actually really tall?” is cute too. She’s so adorable and always completely vulnerable around Iruma, yet she never compromises her dignity as student council president. In Volume 2, when she hit the nail on the head with Iruma’s core issue—saying, “That’s an ideal. What I asked about was ambition. Ideals and ambitions are different”—it was brilliant, and it’s one of my favorite exchanges. That’s when I realized she’s the key to Iruma’s growth.
Nishi: Asmodeus is totally supportive of Iruma, so he just agrees with everything, and Clara doesn’t really think about those kinds of things—she’s just free-spirited and goes “Yay!”—so in terms of encouraging Iruma’s growth, Amelie is probably the best choice. She’s his senior, after all.
And Iruma carries these lessons with him, always. We see it when he confides in Azz about how he wants to keep improving, he mirrors Ameri exactly when teaching the Many Ears about ambition, and Ameri and Iruma constantly reinforce how they inspire each other when they hang out.
However, even though this is an Iruma-centric story, Ameri does have a significant presence in Babyls. We see just how busy her school duties keep her, how much she trains, and how the system falls apart when she's removed. We know that she also pursues her own groth even when we don't see it. After all, she was internining with DBP during both the Evidol Games and the Museum Arc, showing that she's got a lot going on we only occasionally see
Importantly, Iruma is not the only person who Ameri's keen to mentor and assist. Bring up your ambitions around her, and she'll help you see them through (In the Evidol games, it was *not* Iurma's pleading that convinced her to join, but it was Kuromu wanting to achieve her ambitions. Same with Jazz during the Museum.)
And that's not even with the Henry and Merize arc, showing how her birth was a significant moment in the Netherworld's dynamics (Balam's interest in humans, Sullivan learning the translation spell, etc.)
The reason I think a lot of her significant story impacts are overlooked is because, well, she is the series' love interest. It's been upfront about that, but it also means since she's "in the lead," her romantic endeavors and therefore the character automatically draw more scrutiny compared to other potential pairings' partners. That's not to say all critiques against Ameri have romantic basis, there's plenty of other valid ones, but I think it means other characters get a pass where she'd get complaints (like how other characters are even more Iruma-focused). Critics I've discussed her with outright mention they tend to speedread through her chapters, so the parts that show her exercising with her student council or discussing lofty future goals with Iruma are overlooked because the previous pages have shippy moments. How many moments she have circle back to Iruma is a valid criticism, I'll admit, but I don't think it's a bad thing for a long-running story to invest time into its main romantic subplot.
tl;dr Ameri has an irreplaceable role with setting Iruma on the path of growth, she continues to act as a mentor and inspiration for Iruma, she has a life outside of his orbit, has meaningful story moments with other characters, and she's relevant to the larger plot.