You've got two values you want to improve: fair play and fair results.
A sin-bin won't help you much to get fairer results, because the incentives to commit a professional foul that would earn a yellow or injure a player are still there even if there's a quarter-hour penalty attached.
Who really thinks a defender off the field for fifteen minutes is worth the same as a one-on-one on the counter?
And it won't help you as much to achieve generally fairer play as formal, specific retroactive suspensions for certain categories of cheating, professional fouls and dangerous play.
The formality would stigmatise offenders: just imagine the extra reputational harm that being an "official diver" would do Bale or Young. And the suspensions would lose players respect at their clubs and among the fans.