i think its worth to note that a lot of the buffs theyre giving these old champions are mini reworks which update their kits to newer standarts.
so the argument of outdated content doesnt really hold here.
in chogath case, who got updated more than just once with the recent buff to his e they just dont have a clear design direction.
despite the champion being old, hes actually doing well compared to modernized tanks, providing large amounts of telegraphed cc to his team while being a beefy frontliner.
the main issue is, that theyre also trying to make him a juggernaut at the same time and added absurd amounts of base damage to his cc heavy kit instead of trying to support his ability to disrupt enemy teams with rupture and his q.
in case of nasus, i think people arent used to respecting his new power like they should. hes supposed to be a lategame hyperscaling juggernaut. hes supposed to be frightening to face in melee.
its true that his design was outdated, which is part of the reason why he didnt scale as well as he should have, being hard countered by armor and tanks due to a previous lack of access to armor pen/shred (when juggernauts are a class of champions that are generally known for being able to fight tanks).
but now that his design is updated and he scales like he should, it created a shock where people still need to get used to the fact that an 800 stack nasus WILL obliterate you in a 1v1 situation and you wont be able to cut down the damage on his q to 25% with 2 armor items.