Bodkin arrow archers - they rape you in 3 seconds.
But seriously, I think moving damage type to arrows was a great change. There is still some internal balance that is probably needed between bows and arrows (I agree horn bow looks a bit too strong right now compared to the other bows, I have yet to test it but will when I retire next) but allowing more variety between bows was great.
Maybe adding a difficulty requirement to certain arrows might help curb the possibility of a super fast super low end bow that fires piercing bodkin arrows?
E: Oh yeah, and about those pictures above? That was always possible with 1 slot bows, provided you take only 1 stack of arrows. That archer only has 15 bodkin arrows (a few more if heirloomed). 1 stack isn't going to last very long.