He was the Lucy to Vakama’s Charlie Brown, to put it succinctly.
I personally like Kopaka. Sure, he’s just-like Tahu in the sense that he’s argumentative and divisive, but there’s an interesting contrast between the two: Tahu’s arrogance I see more like that of a bull charging for the red cape, and then having to deal with the fact that he’s stumbled right into the matador’s trap, whereas Kopaka is the type of guy who would stand back and smirk smugly to himself about the “idiocy of Tahu’s actions” (I especially like the two of them as I’ve seen them portrayed in some fan-films where the Mata’s personality traits are exaggerated to make to conflict/humor).
(On a side note about Kopaka’s scenes with Pohatu, I enjoy seeing their arc as that of a “buddy-cop” story of two guys who don’t get along real well at first (even if only one of 'em thinks so), and then eventually learn to get along as brothers and good friends, having grown as individuals as well for having to deal with rubbing abrasively against each-other: Kopaka having to learn to work with others after the toa whose behavior possibly irks him more than any other’s won’t leave him be, and Pohatu also getting a character arc of learning to be friendly without annoying his bro(s) so much, resulting in him getting some character development, instead of being portrayed as a “perfect” character who never had any flaws.)
Yup. That attitude of “We’d all get along if you’d just stop doing that!” is a flaw that I might’ve seen her portrayed as having in fan works, and I think her character’s all the better for it. I know from experience of being a sibling that that attitude is something people with brothers and sisters have had to overcome in real life as they were growing up, or otherwise risk the arrogance or resentment of “I always have to pick up your slack around here” taking root.
I’ve seen a fan work that takes her character in a new (albeit likely temporary) direction in a retelling of '01 where she eventually has had it and goes “You know what? If my brother’s gotten all his masks while ignoring what I’ve preached so hard while I’ve fallen behind, then I can strike out on my own and do it, too!” which blows up in her face, and causes her to have an introspective character development moment.
I’d personally find it quite interesting to see her character portrayed as someone going “I’m clearly right! Why do you keep ignoring how right I clearly am?” (a contrast to Onua, who’s wise, but whose flaw might be that he doesn’t feel the need to tell others when they’re wrong to such an extent that he might end up going to the other extreme of letting others make mistakes for themselves too much/hard) and having to learn to overcome her need for acknowledgement and learning the lesson of “They don’t care how much you know until they know how much you care”, converting people to a correct viewpoint not through arrogance, insults, and lording it over them, but learning to “break the bone” by a soft tongue.