Slow motion makes soccer referees more likely to give a red card. Video assistant refereeing in soccer has to be used with caution. Researchers have shown that refs are more likely to give red when they see a foul committed in slow motion, even when a yellow card is more justifiable. This is because fouls viewed in slow motion appear to be more serious. Source 4e.
I dislike this use of slow motion or even instant replay to assess a penalty. I say let the game be as it is now and let the players play the game. If a player is out to cause injury to another they will be red carded. Most players are not going out there to cause injury and just play the game.