So, if I'm an 11th level Fighter, and I want to hit the goblin in front of me, move ten feet, hit the goblin over there, then move my last twenty feet and hit the goblin caster in the back, it seems that by your suggestion I cannot do this.
It's an interesting idea, but I feel it makes things more complicated, slower, less intuitive and actually less tactical and flexible overall than normal 5e rules.
