[ister]

Ugh. Let me try again. Damage from darts is better than damage from slings unless you're a fighter with exceptional strength (i.e., 18/xx). For mages and druids they are by far the best missile weapon (where by 'best' I mean that they inflict the most damage). For fighters they are competitive with slings unless you have specialization or are above level 7.

It's just wrong to say that the damage is useless. Simple table at base APR without strength modification:
Damage per round:
composite bow - 6-16 x hit prob (average 11)
short or long bow - 2-12 x hit prob (average 7)
heavy crossbow - 3-10 x hit prob (average 6.5)
light crossbow - 1-8 x hit prob (average 4.5)
throwing axe - 2-7 x hit prob (average 4.5)
throwing dagger - 2-8 x hit prob (average 5)
sling - 2-5 x hit prob (average 3.5)
dart - 3-9 x hit prob (average 6)

Now strength bonuses and specialization count against darts, as will higher warrior aprs at higher levels. But the damage is just fine.