Yea so you are saying that I am right?
Just use quick cast and it will be faster.
Also, certain ultimates are designed to be quick cast because their utility is tremendously diminished if they are not.
Darius ulti is channeled and can be stopped. Naut's ulti is instant cast but it's very slow. Akali and zed are assassins who their ulti's affect one person. Cho'gath's ulti affects one person and is close range. Caitlyn's is a channel. Camille's is not instant because she becomes unforgettable momentarily. Veigar is a burst mage. Why would you even bring him up.
Lee Sin's ultimate is a channel and it can affect multiple people. Lee Sin is not weak at all right now. Lee Sin is a bruiser.
Like I said, if Lee Sin were in a bad position right now, then sure, give him that buff. He is quite good right now.
Imagine how useful it would be to pros if that happened. Lee Sin would be banned every game.