Those aren't exactly fair comparisons though. Both of them have high mobility, high reliability, and consistent damage even outside of their ults. Illaoi has literally none of that. Heck, Azir's case is an even WORSE comparison because when he first came out he was legitimately weak. He had tons of bugs, some of which weren't even ficed til a year after his release.
I do understand your point. But I'm hard pressed to buy it when a large majority of players don't even play against her right. She is terrible high elo because of the issues inherit with her kit. Azir was bugs / skill issues (he took people a long ass time to master) and lucian historically hasn't ever really been a bad choice. He was a generalist pick that was too strong for a long while, they reworked him to be a more close range adc, and they JUST nerfed him becauss his range was still too strong.
Better champs to compare Illaoi to would be other melee champions with heavy damage, low mobility, and either next to or no cc. Darius / Mord would be better comparisons, but even they don't fit properly because they aren't forced to stick by zones (tentacles) to fight, and they can still do decently without their ults mid fight.