All bows and crossbows in fantasy are woefully under-powered vs their potential battlefield effect. Range of 30" in longbows is shorter than it should be compared to other weapons due to the ballistic trajectory. And longbows were as lethal as many inferior weapons.

In 8th ed, even S3 weapons COULD kill a T6 dragon (in fact it may actually be better value for points to use them in this capacity than to target say AV3+ Chaos warriors!) but as an anti-infantry weapon, the longbow is useless whilst the crossbow has zero manouvre value, its an area-denial weapon only.

Experimental rules - Longbow, bow (not short bows, these are more direct fire weapons)
Longbows and bows using volley fire are armour piercing. The shots coming down from a high ballistic arc are more difficult for an advancing enemy to block, and more likely to hit unprotected parts of the target.

Experimental rules - Crossbow. Units armed with cross bows may move and shoot, but must then forego shooting in the following turn as they reload their weapons.