Alright Riot, I'm not sure if you have a pen /paper handy but you're definitely gonna wanna write some of this down. For todays example we'll be looking at Aatrox , the champ that never needed changing.
To begin, lets remember what a 'remake' is. A remake is when you take an existing champion, and due to some mechanic in their kit, they need to be remade to either tone them down or power them up. In the case of Aatrox i'm not too sure if he was too weak or too strong, I mained him myself and from my perspective he was quite balanced. Needing a good level of skill/knowledge to know when to engage, how to pop bloodwell, kiting, bursting. Was strong when played correctly, weak when not.
So lets just assume Aatrox was a huge problem in League and really needed a rework (which he didn't). When redesigning a champ, retaining their core gameplay elements is crucial, otherwise you aren't remaking the champ, you're instead creating an entirely new champion that just looks similar. Looks aren't important, gameplay is.
How did Aatrox play before? His Q was a gap closer/escape (which could be cancelled if used too predictably/early), a W which gave more damage or heals, an E which allowed ranged poke in lane, and an ult which synergized with his W.
How does Aatrox play now? He has a Q which can be used 3 times, deals great damage but no mobility, a W which shoots a skillshot that creates some area that pulls them back in or something dumb like that, an E which is literally Riven E but provides no shield, and his ult which really takes the skill out of using Aatrox passive. Admittedly combining Q with E to extend range is cool, but again it's a simple mechanic and doesn't fit the theme of what Aatrox was.
When we compare Aatrox before and after the rework it's obvious they changed the way the champion is played. Going from a fast, attack speed driven hyper-carry, to a clunky slow champ with a huge sword that uses no autos and is primarily ability based.
All in all I get Riot isn't trying to ruin the game, and I'm not saying they are. But sometimes I really struggle to understand the root of their decision making. I'm fine with remaking champs, and items, but if you don't have a clear vision and why/how you are going to implement those changes and how those changes will effect the playerbase, then just wait till the golden idea comes. Aatrox was low playrate and if anything was gaining popularity because people finally noticed how great he was, then Riot just changes him as if he was super broken. Tweak his numbers, take down some of his burst, reduce HP gained from passive, anything would've been better then gutting one of the few unique champs in the game.