Umpires will get it wrong, they'll see what isn't there at times, misjudge the amount of contact etc. The players fundamentally need to just get on with the game and there is zero to be gained from arguing after the fact, right or wrong call made.
I disagree with the bolded. If it is clear to an umpire that they paid a free kick to a flopping diver, then next time in that game they see said flopping diver flop to the ground, they might not pay a free kick. Sure, the players could have told the umpire he dived, rather than pointing at the screen, but the umpire watching it on the screen would have more impact. I suspect umpires are instructed not to watch replays, whereas they should be instructed the exact opposite - watch the screen after you pay a free kick and see whether with immediate hindsight you would pay it again, and learn from that so you improve your performance throughout a game.