As much as CertainlyT does create balance problems and overloaded kits...
We do have him to thank for a lot of stuff. The fact of the matter is, he was the first designer to understand that a game with 120 champs (or however many there were around thresh/darius time), it was time for some innovation. Did he go overboard (especially on kalista)? Yes. However, he has allowed other champion designers to look at his designs and think "huh, maybe that will create balance problems... but let's try some innovation!" Without him, champions like bard who IMO is really cool design and is not imbalanced would not be possible. I know, I know, we all hate kalista and it's fun to rag on him. and hes pretty bad at balance (no offense, bro), but without him league would not be as poular nor as fun to play. Sure, it's fun to reminisce about when every champion was simple and balancing wasnt hard, but let's be real: do you really want a game with no fun/ unique champions even if it is better balanced? I say no - the balance is an issue, and CT takes it too far sometimes, but he has evolved the game into something that it probably wouldn't be without his creativity and the precedents he set.
EDIT: Thanks for all the replies! Couple of things i want to say:
#1 - I like that this is promoting healthy, non-circlejerky conversation where all posts are getting up/downvoted not like 30 with 100 upvotes and then like 2 with -20.
#2 - CT is not DIRECTLY responsible for really well designed champs like bard, but he was the first one to challenge what a moba should be in terms of simplicity.