I think it's been abundantly clear that roster updates fuck too much shit up to have been healthy for the game. The Juggernauts created and broke Cinderhulk, while champs like Garen, Skarner, and Darius had their kits overhauled to overly good success and overly bad failures. The Marksman one created monsters of Kog'Maw, Graves, and Caitlyn, all of which had to be heavily nerfed, and in Kog's case, partially reverted. Same holds true for the assassin update as well - Rengar is getting reverted, and there's talks of LeBlanc being reverted as well. The mage update also saw Malzahar changed and partially reverted, and throughout all of the updates, heaps of items broke to astounding levels and have been balancing nightmares.
Roster updates are dead and should remain dead. They brutalized the game way too quickly and leave everyone with whiplash. It's also notable that a lot of the things that were changed in those updates ended up reverted months-years later after they were so OP or so UP that they couldn't sustain themselves.