chogath hasn't been changed in years and is mostly fine
in fact, he is vastly preferred as he is now because he's one of few champions that can prevent an assassin from utterly annihilating you at any point in the game and makes a great overall pick without directly affecting the game
he can chain crowd control, yes and he does a lot of damage, yes, but he is a champ that telegraphs their movements(unless coming from fog of war or bushes, but anyone can ambush you that way)
he is also currently one of the only champs capable of playing every role on the team(though inferior in jungle, he is capable of the role well enough)
if anything, riot needs to improve the older champions (like they did with Sion but much less overkill) so that there are more counterpicks to flavor of the month champs
for instance, graves used to be a top pick because he was highly mobile and had great burst damage, now, how often do you see a graves? his range is very low in this meta, his burst requires specific conditions to be met, and his passive requires him to get into the "kill me" zone to even be activated
also, chogath gets all of his damage because he is the least tanky of all the tank champs
champions like twisted fate, Kayle, swain, and many others are in need of reworks and buffs, instead of riot nerfing the currently viable champions
Kassadin kind of deserved what he got(because he could do anything) but he is now unable to do much of anything
if he's level 18 and has 40% cooldown reduction, sure, he gets a 1.8 second warp, but he has to get so ridiculously close to even use it that he basically functions the same as Khazix now with less effective build paths