Alright, so after being asked to post here with my opinion, why anyone would want that completely bypasses me but none the less, here's my opinion.
I'm at a crossroads to be honest... On one side, you've got the arrows determine the damage type, perfectly acceptable in the realworld. On the other hand you've got the gameplay and balance argument, whereby different sub-classes of each class should be specialised in different areas, having the ability to pick more damage for a sub-class that previously didn't specialise doesn't make sense from that point of view.
The game has got many different types of weapons and armour interlapping over many different time frames.
If you think about it, and please don't go too deep into things here, but Bodkins were used against mail & plate by the British since they were more adept arrows at piercing armour while more "khergit style" people you were more well known for their horse archery skills would have been fighting people with lighter armour, more easily cut so cutting arrows would have been much more useful.
Now, we all know that this doesn't happen within cRPG because of the crossed timezones and armour types, pierce has always seemed to be better across the board with more of an advantage at the heavier range of equipment, makes perfect sense but when you start allowing bows that would never have fired a piercing arrow because of what they were designed to fight, it starts to become a grey area and you have to stop thinking about realism or even logic because it's perfectly acceptable to say "all bows can fire all arrows" because unlike for example, crossbows or guns, the bolts/bullets need to suit to the barrel size etc, I mean, if you had a twig, you could effectively fire it from a bow, but try shoving one into your gun and you know it's not going to end well.
From that point, it brings me to why I believe that from a gameplay point of view, having bows with different abilities, in this case, the longbow being the only bow to use pierce damage, makes sense, it's a lot slower than the cutting bows, it's got only slightly better range than other bows these days and therefore needs something to identify itself as being a worthwhile weapon other than it's stunning good looks.
I find it rather disconcerting that people are able to run around on horseback using bodkin arrows, Horse Archers, and please don't get me wrong, have always been a sub-class, one that is there to get its kicks from being a massive pain in the arse, they should be able to get kills but they shouldn't be firing at heavy armoured targets because lets face it, they wouldn't be in their set time zone.
With regards to that, taking the horse archery bows onto foot again, the same thing really, these bows are supposed to be fired quicker and the way the game balance works for these is that they're supposed to be the fast weak bows that are still viable to kill, while the Rus Bow is the mid-way bow, reasonable damage and reasonable speed at the cost of 2 slot while the longbow is the "damage god" but uselessly slow.
I honestly still don't have many problems with the horn bow/tatar bow wielding horse archers/footarchers but that's just by the way I play, i'm not exposed or helpless against them and therefore can dispatch them pretty effectively while melee will see them more and more often because basically to be frank, you're bloody easy targets with your lack of shield, slow movement speed & lack of spacial awareness.
In short, arrows dictating the damage type needs to be tweaked at the very least, not a fan of handing out buffs to sub-classes of archery that really didn't need them because they chose those sub-classes in order to play the way they wanted, doing more damage just increases the incentive to go for one build over another. As I said, the longbow being the only piercing bow allowed for people to go specifically for a longbow build to do high damage because they wanted to play like that, if they wanted to be faster, then they went for the hornbow/rusbow.
I hope that makes sense, but in short, I really don't care about what happens as long as the longbow stays piercing although I do like the idea of the "arrow logic" but the gamebalance appears to be, from a melee perspective, to be buggered.