Yeah, but RBM is a band-aid. There should be ways for the AI to protect itself without needing big armor values. In fact that to leads something I dislike about RBM: units with looots of armor (so all top tiers in Native Bannerlord) are a pain to kill, not because they are somewhat competent but because they are DPS sponges.
With archer fire doing slightly less damage, better armour and formations, we'd end up with something much more enjoyable: arrows (and bolts) can stilll deal a massive amount of damage, especially on unarmoured units, but can also be consistently be protected from (proper shieldwall and blocking, so no attacking a dude 5 meters away that's already getting gangbanged).
In that situation, focus fire would actually shine (I'm only talking about SP, reminder): because it would be actually rewarding! Finding the weakspot in the formation, or even using focus fire on skirmishers to break shields before sending the arrow shower... Mind you, we would also need to basically use the RTS Camera features...
Without functional armour, proper formations and competent AI soldiers... giving more tools for archers is a mistake, imho, because everything even further off balance in favour of archers. I would want to see it happen, mind you, just not right now.
Mp is another story, as other more informed forumites have stated, and it could even be testing grounds for the feature (which, let's be honest, doesn't sound like it would be hard to implement...).