Interesting, very interesting.
There is a world of difference between a Thrown Knife, Thrown Grenade, Launched Explosive, AE Spell... IMO.... using real world physics v/s how the rules behave.
A Knife, Dart, Baseball, are all thrown directly at you, usually with as much force as possible.
Grenades on the other hand, at least according to my Basic Training Instructors, are lobbed.
We got yelled at for throwing them like baseballs or footballs or any thing from the shoulder or waist (sidearm).
We had to stiff arm toss them UP & over like you were one of those plastic army men from child hood.
It was really annoying actually, not at all natural, BUT, meant to teach us how to get it inside of a fox hole or sand bag emplacement & not bounce around rolling past the enemy or back at us.
The timed delay of them to me & that slow arcing toss is what is represented by the RUN chance you get with AE's.
I don't really see it applying to a Knife OR for that matter launched explosives/spells that are moving fast & explode on impact.
But I guess that was too much for the rules, so I'd rather see it work on all the AE's since as a general rule most of the AE's are overpowered. (Not Direct Spells like Stunball, but the Indirect are for sure)