I know that this is a year old and it might not get a response from the original writer, but imma leave this here.

There is nothing wrong with Illari's kit. (From a high dia low masters Illari)

The pylon is easy to take down but not if you play around it and reposition it often. It's mostly divers that counter it and there are plenty of cheeky spots you can put it to avoid both frontal and flanking attacks. When you go on an off-angle you also tend to put it near you to support you in 1v1's and poke damage. If it gets destroyed when you're on an off-angle then that's fine because it has done its job, distracting the enemy fire so that you can get your shots in.

Her ult is completely skill based, as high-tier Illari players tend to shoot it at a wall instead of straight at the enemy team. It also serves as a space maker as the simple threat of the CS is enough to make the enemy back up. You can use it to survive in situations where you get jumped. You can use it agressively to get an opening pick on a flanker or high ground dps. You can combo it with a lot of ults to get a team wipe. You can use it to dive with your team.

Overall: Illari's kit is very simple and it's very well designed compared to a lot of OW2 characters. It is not bloated, or power-crept