Well, thanks to the extra_penetration flags we can effectively create 2 soak/reduce parameter sets. That's what we done, we gave all bows and crossbows those flags, making them more or less behave like it was prepatch against armor while melee and throwing uses the new parameters(less soak/more reduce). One reason for that was to let tincans keep their soak protection against weak bows.(I know, archery dead. We have an eye on it. Crossbows got their nerf too. Ask Dave, mention precision.)
The decision to let throwing behave like melee instead of the other ranged was a last minute one, but I think it was right. One grief throwing caused in earlier patches was the occational (body) one shotting done even against heavy armor with throwing lances. This more rare now. It could be rather frustrating because of the rather high agility of throwing in close combat along with the accuracy buff.
A pseudo, made up on the spot justification could be that crossbows and bows shoot projectiles with rather high speed and thus high kinetic energy(1/2*m*v^2) concentrated on a small area(tip) while having a comperatively low weight and thus impulse(m*v). So if strong enough they should perform well at overcoming armor(lower reduce). However the low weight/impulse leads also to the fact that an arrow that is not strong enough to penetrate doesn't bother the target much(high soak). Thrown weapons on the other hand are rather slow in the air but have a high weight(high impulse). So even a throwing weapon that does not manage to penetrate the armor has a better chance of causing a bruise or putting the target at least off balance(less soak). In return penetrating the armor is not as easy(higher reduce).
Of course this argumentation is full of holes(role of weight in armor penetration) and does not very well explain why throwing stars and daggers should bounce less now(180 wpf grief STF throwers getting rolled as you read this) but I like the outcome that the strongly accu-buffed high end throwing weapons are not that good at overcoming heavy armor as before. Personally I'd give a seperate soak/reduce/friction parameter set to every weapon but we are very limited with Warband. At least without WSE.