Good points, but I think archers are understated a bit. A pure archer setup is much cheaper than a melee/crossbow hybrid.
Woot ? Our arrows break every 2 rounds, and as a pure archer you have two stacks of them.
On the contrary, a melee/xbow hybrid has 100 wpf in his two weapons, so nearly as much break chance as the bow.
Also, being able to efficiently use a melee weapon, means you can pick one up on the ground, starting with just a nordic sword, for example. This is a big advantage.
As a pure archer and 0 PS, i often have the time to shoot my 40 arrows, pick up and shoot others, then fetch a beautiful 2h weapon, and die glancing.
Archers are excellent when cooperating with one another, and versus cavs.
In all other aspect, xbow is superios. Even in no-cover maps, you can find a willing shielder to cover you, and when the xbow reload, he can view around him, so no tunnel-vision, and he's lower, so less hit chance.
Finally, you can dodge arrows. You can't dodge bolts. You can feint them, but you don't have the time to see them and change effectively your trajectory, unlike against arrows.
TO OP :
You realize there's already 2 slots bow and xbow. Making all other range weapon 2 slots, without buffing them in any way, is definitely an overall buff for the "old" 2 slots. Or a nerf for the others. That's not balanced.