A problem with the lore.

What do you mean by no reason? They changed the summoners and arena type lore because it was them attempting to explain the game and not a actual story. With the new lore they are updating it so older champs with the summoners in their lore they are trying to make the champions have lore that feels apart of the world Riot created. For instance Volibear in Ornns lore is not just a bear with thunder powers he is now a Ares type of character that can have very good place in lore when its updated.

I dislike some champs being forced in factions or changed completely from the things that made them interesting.

Old trundle was good then he went cliche troll king.

Xerath was a man basically born as magic incarnate, he wasn't evil or out of his way good. Was a nice shade of grey like a scientist trying to survive in his mortal shell.

Also riot is just adding a lot of edge to champions getting rid of the goofy charm.

Oh I think they have reasons. I don't agree with many of them but they definitely have reasons.

A big one would be: they think this story would be more interesting.