Instead, I see the defender always has two options: Dodge (Either through awareness, or seridipity), or tough it out. Just because it hits doesn't mean it hurts. Personally, in situations such as Ranged attacks, I like rolling a 10 on a modified d20 roll to determine a projectile's trajectory. Ranged combat is somewhere the abstract gameplay of D&D really shines. There are far too many variables to write a trajectory fairly.
Of course, this is just my personal preference.
Just a note: I have a d20 on my side of the screen. I'll be using that when determining the outcomes off attacks against my character, and even reflect the outcome in my description of attacks against foes. (I don't character control, but still give an indication of how effective my attack should be)