Guys he's not talking about a skill that is in game, he just used Morgana's Q as a range reference.
As for my own opinion only executes should be anywhere near being a 100% kill skill, and they often miss the mark slightly. You can add as much baggage as you want to it, but it will never be balanced if there is no counter play. Other skillshots of that range have various weaknesses, like keeping the champion who used it from attacking for a short time (Thresh), cleansing (Morgana, Lux), or being blocked by minions (all of the above).
A skillshot that is either a kill or a miss will never be balanced, particularly when the additional baggage to try and balance it is easily done with a macro.