Exactly why RTWP is frustrating and doesn't always work for many players. When a player sees that a goblin is 30 feet away, and they tell their four characters to run up and attack that goblin with melee weapons, it is very frustrating when the goblin runs away at the same time, keeping his distance so the four characters can't ever catch him and hit him with melee weapons. If the PC wins initiative, the player wants the ability to move their melee person into melee range so that if the goblin tries to run, an attack of opportunity is done. Thus, the player gains the upper hand and makes good use of their melee person.
But that's the problem with this kind of combat mechanism. If I tell Lae'zel to run 30 feet and do a melee attack against a goblin, and that goblin simultaneously runs away, then Lae'zel's turn is wasted. She's not a good ranged person because her strength is in melee. So if she can never reach her enemies because they are always running away and shooting, then that sucks. And if the player is forced to program in their characters' actions BEFORE the round starts, then if Lae'zel sees the goblin running, she can't suddenly switch to Dash to catch him.
This said, IF someone was to implement this kind of gameplay mechanics into a video game, it would only work if the player was allowed to input a primary and secondary set of actions. So, primary action would be run 30 feet and do a melee attack. Secondary would be, "If primary is unable to be done, then do secondary."
So, in the case of Lae'zel not being able to get within melee range, the primary action would be run 30 feet and attack with melee weapon. The secondary action set would be to run 30 feet and shoot with a crossbow OR run 30 feet and then Dash and run another 30 feet to get into melee range of target.
That actually wouldn't be too hard to implement. Each round, the player would select the PC and then select a target; let's say Goblin 1. The player would then provide a primary action, like Make Melee Attack. The player would then provide a secondary action, like Dash or Ranged Attack. If the character can do Bonus actions, like Off Handed Attack, the player could also put in the cue a Bonus action as well. So, when the Round Begins, if the character can't run within melee range and attack, the primary action, they will do the secondary action, like Dash or Ranged Attack.
This type of gameplay would also make it so players can't shoot a crossbow, run up to an enemy, switch to sword and shield, and gain the AC advantage of having a shield during combat. Thus, it would be more strategic there as well.
I do think this gameplay style might be fun to try. However, I think there would be many problems with it. The AI would have to be intelligent enough so that your characters wouldn't run through hostile terrain and such in order to try to catch a moving enemy. So, for example, if the goblin Lae'zel was running 30 feet to attack during melee decided to run sideways 30 feet instead of away from her, and by doing so that caused her to catch him, but she had to run into an explosive mine to do so, I'm fairly certain a player might get pretty ticked off by that.
But if the game was smart enough to have characters avoid stuff like that, it could work. Certainly, combat would go quicker since the AI would be calculating enemy moves at the same time the player was cuing up all of his party members' actions/bonus actions.
