I think the it will remain part of the game
The one area where it seems unfair is Braithwaite smashes a six then retires. An old school playground rule where if you hit it over the wall you had to climb over and fetch it from the neighbouring garden or you were 6 and out.
The bowling side could be allowed to select a bowler who has used up their allocation to return to bowl (e.g. in a 20 over game they'd get a 5th over or 5th set of deliveries)
It shouldn't occur 3 or 4 times as it is only going to be used towards the end of a shortened already short format game although what's to stop 2 players retiring out at the same time or if there is a run out and the other batter retires out bringing 2 fresh faces to the crease.