Honestly, I'd rather have my favorite champion exist but be low tier than have them basically removed.
Sometimes they get it right, creating a new character that still respects and hits the same points that the old mains liked.
Heimerdinger and Taric were probably the best ones in this regard.
Sometimes they fuck up majorly, creating something unrecognizable.
Sion, Aatrox, and Galio fit this to a T.
While I think the Sion thing was for the best, and that the new Aatrox/Galio are cool in their own right, they don't fill the hole.
That kind of thing can make somebody quit the game for good.
I know this because it's exactly what happened with me and Overwatch.
Bastion, Roadhog, Symettra, and Torb all lost the things I found fun/satisfying about them in the first place, and now I don't find any of the remaining heroes fun so I just don't play the game anymore.