Would you rather have a bunch of crossbow men or a few trained archers (me and my girlfriend got into the discussion after watching Robin Hood) Bows take a lot more training to use and their arrows are a lot harder to make then crossbow bolts but are more accurate and longer ranged; crossbows are cheap "simple point and click interface", the only hard part is cocking it (lever or wind up , or simple pull back, the bolts are just small wooden spikes, even with training, are less accurate and shorter range then arrows. Basically this boils down to quantity(crossbow) vs. quality(bow). Oh and crossbows, and with the exception of those giant overpowered mounted crossbows, could not pierce any but light armor.