The mobility of ward jumping then landing q and traveling to the target is literally unmatched by anything else in the game especially if you consider how many wards a Lee sin player can have. You can have the area around your lane lit up like a Christmas tree and never see Lee till he's flying at you. Throw in the fact that his R let's him move an enemy on top of it? Busted. Build cinderhulk, ward hop over wall, kick enemy to laner, q to enemy and out of turret range, collect gold.
I don't understand how people can continue to look at that kind of unparalleled mobility, displacement, stickiness, and damage in aggregate and not admit that there might be some validity in saying his kit is over powered as it stands.