Scenario:
I swing at an enemy, then I ready to move away when they start to swing at me... The enemy starts to swing, I move away, they've wasted his first attack action on someone who's no longer in their reach.
These scenarios could crop up in 1st edition too, though it's a bit more pronounced here as you can take a single regular action, then ready. It'd be nice if this was fixed as part of the rules.