Rangers charging across the field as a 1st line of defense get killed. Enemy archers will eat them up along with common Strength 3 infantry. The extra 6" range means nothing in this case. Dwarf archers you can leave exposed.
The Dwarf Archers kite other archers since they will want to be within half distance to hit on 6's rather than 6/4's.
Assuming your ATD/Heroic Shooting, that's plenty of movement to kite. You can't kite otherwise (whats an extra 1/2")
Shortbows is not a big deal if they are in the front. You lose 3" if you hide them in the gaps in your second line anyways so its not as far back as you think. Dwarf Archers have a practical use and since Dwarves won't have numbers, a utility like bows and Def 6 is quite handy alike the Osgiliath Veterans.
If the front line gets mashed, they achieved to solve another weakness which is movement (getting in the fight). Plus if they face an enemy that likes to sit back, Dwarf Archers can Herioc Move till within range, hold the line till the rest of army arrives.
You don't charge your archers across, you hold them back to unleash hell!
But you want to be within short range too, which requires another turn of marching, so they kite you, instead of the other way around.
It is far more usefull to just get some proper combat troops and some proper archers, instead of these, who do both a bit, and as a result fail in doing either.
Why don't you just Heroic Move the rest of the line up?
"... Telchar wrought it in the deeps of time."
-On Andùril, The Lord of the Rings