Old Lore Vs New Lore
So it has been a little over 2 years since riot decided to scrap the old lore and replace it with the "new lore" They did this because they claimed that the institute of war was limiting their design space. Before we look at the champions that have since been released, lets look at the lore itself.
First of all, the old lore said basically there are these powerful mages called summoners who basically mind control creatures in the place known as summoners rift where death isn't permanent. They would host battles here in place of actual regular war. This is done to save lives and stuff. Under this system, champions would sign up and basically give their life to the institute and then the summoners would select the champion they most liked to fight for their cause. This is how you could have noxians fighting along side with a demacian, because they werent in control of their body. They might have even been fighting against their cause, but they were fighting in the system and that is what made it ok to them. The institute of war was also tasked with containing creatures that would be absolutely out of control. For instance, Cho gath. Cho gath was basically a world eater when he came from the void, the summoners contained him. When you choose cho gath, he says "you wish the world you know to end? YES" because he believes he can break the summoner and get free. Some Champions are there by accident, like ezreal, he is like 12 years old but they summoned him because his bracelet interacted with the summoner magic by accident. Nasus and renekton are both in the league because someone wanted to summon one of them but accidentally summoned the other. There are a lot of different reason for a champion to be in the league and it is very interesting if you are into that kind of stuff.
The New lore basically says ok, this is the rift where death isnt permanent and people fight each other there cuz why the hell not. This explains literally nothing. Why might darius and garen help each other? How is cho gath not destroying the planet? The New lore doesnt really explain anything.
Lets now look at some of the champions they have since released.
Taliyah. Her current lore basically says shes been travelling the world looking for the meaning of life and how to hone her powers but then her home town is now under attack and she needs to return to defend it. Her home town isnt the rift, so why is she there? It would make more sense in the old lore if she basically just joined the League to hone her powers.
Aurelion Sol. He is a powerful star dragon but his power has been limited by the mount targon. He wants his power back. I guess he might be at the rift maybe to get power back cuz its where taric... but wouldnt he want to go to Mount targon? Instead in the old lore, he could be a star dragon that just saw runeterra and said i wanna screw shit up over there then the summoners need to contain him.
Jhin. An artist. His craft: death. Currently he is a hired assassin for the country of ionia, but why would they send an assassin somewhere where death isnt permanent? Instead he could have joined the league to just make a bunch of art.
Illaoi. just a kraken priestess on a rampage, honestly makes as much sense in the new lore where she does it for fun as it would in the old lore where she would join the League to go on a rampage.
Kindred. The spirits of death. They travel runeterra basically just ending lives. in either lore, they could see that death isnt permanent on the rift and decide they need to investigate because obviously something isnt right. Then in the old lore they get trapped there basically.
Tahm Kench. He is hungry, he wants to eat, in the old lore, rather than him having to hunt for his food like he needs in the current lore, he wouldve joined the league intentionally just so they could basically bring the food to him, and the summoners would accept him with open arms because he is eating people and that is frowned upon in the establishment.
Ekko. He was on the streets of zaun, he would join the league in the old lore just so he can have a place to sleep and a meal every day.
Rek sai, kalista, Azir, gnar. All would just be contained by the summoners because they are a danger to the world.
Basically, i dont think the old lore was limiting the champions at all. But not only that, the new lore makes no sense either!
An other thing that can be explained in the old lore that cant be explained as well in the new. Gold. in the new lore I guess you kind of loot the corpses of what you kill... but why do jungle camps have so much gold? also, why dont champions lose the gold their killer earns by killing them? In the old lore, the league of legends can also be a sort of spectator sport and people are cheering on their favorite champions on by funding them (the passive gold flow) and then rewarding them when they do well (killing things)
Basically changing the lore up 2 years ago was a total mistake. It wasnt really limiting like you said it was. The old lore provided a lot more purpose to the game. Please go back to the way it was.