Estinien (spoilers)

[Ibi]

Did you literally miss the part where he actually DID suppress the eye, several times, when he needed to? He had one job and he believed it was done when Nidhogg was dead.

Given that he's failed to suppress before and considering how serious the consequences for failing are, most people in his position probably wouldn't be so certain that there's no way it could possibly happen again.

Besides, Nidhogg was already dead for some time when Y'shtola gave him the warning that the eye was still attempting to take control of him. If he thought the job was done when he killed Nidhogg, at the very least that should have told him otherwise.

It's almost like only players feel they can be cocky and arrogant or something?

When in the MSQ is the Warrior of Light ever cocky or arrogant?

Estinien had such good development and people get upset over it.

It's your opinion that he had good development. Other people have a different opinion, which is why they get upset.