The problem with Class Updates
First I just want to say, bless papa Riot for not going down with anymore Class updates. Almost every single update has been considered a failure for the most part with only a few champions being successful out of the like 20 champions affected.
Now to keep it short and sweet, the main issue I believe to have been the cause of many of the negative experience players have had with the champions is simply due to one factor. ** All the changes feel rushed.**
I mean I can't blame Riot. They had to meet these class updates to mid and pre-season, so that means they had to rapidly select the champions, figure out the problems, and try and make changes that would fix the problems all within about 6 months. Now for some people this doesn't seem like a lot of time. "Hell, six months? I could do that!" some are probably thinking. See one important aspect to consider is they often did 3+ champions and in that short time frame often had other changes going on at the same time as well. Marksman update was massive, changing nearly every marksman and I can honestly say, none of them were that amazing and some were crazy broken. Graves was cancer for nearly a year, Kog needed to be reverted, Quinn is a mess of a champion, along with many other little changes that just left champions either overbearing or...odd. Really that was the problem with the class updates. They never gave the changes enough time to really figure out what was the right course to take and often missed the mark.
Zac had one of the most fun and interesting ultimates and yet the change made it weird and just awkward to use. It made his Q one of the most reliable CCs in the game and kept a lot of the other aspects that made him strong. Sejunai is disliked by many players (I do kind of like the updated compared to old sej) but it has been such a balancing nightmare that she is now so weak outside a passive that was already easy enough to shut off that I have no reason to play her. Rengar and LeBlanc are just memes that people still cry out for in deep need of help. Many of these changes don't feel finished either. It feels like you want for the first draft of ideas, sat with it and just didn't have the time to fix it or try something that could have been ultimately better.
Class updates never felt good because they never had the time to truly understand a champion. They never had the chance to sit on the changes and see if hey, are these actually good or not? Riot doesn't want to admit it but let's be honest guys, rushing a project out every 6 months that effects massive amounts of players and could leave a sour taste in our mouth just isn't good.
Compare that to Xin Zhao, a champion that a couple of months, I wouldn't touch with a 10 foot pole. Easily, one of the most enjoyable reworks I've played in recent memory. Rek'sai, Azir, and so on, all the same. Although Riot says yes, these are who we are working on, there is a passion behind it and most importantly, no deadline. These changes are given the time they need to sit and really go through the chopping block rather than the Class updates which need to hit at a certain point and were expected to solve a ton of problem.
Never do class updates Riot. At least if you are, don't commit it to a deadline. Take your time. Perfection doesn't, and never will, come from a rushed product.