The problem is not the OTK and Combos. The problem is Reno decks where you have to kill the opponent twice in a game and 3 times against Mage. OTK and Combo decks have a better chance against Reno decks. Take Reno out and the OTK and Combos are likely to significantly diminish because the format will be faster.
Thats the only thing that still holds control decks and you wanna delete it for faster games ? That is the problem with wild super fast boring useless games.