Why is crossbow damage based on ST?
The damage done by a crossbow is based on the ST of the bow, not of the firer. A PC may fire a crossbow stronger than his/her ST without penalty, but cocking the crossbow will take longer (p. B114). GURPS Vehicles, Second Edition has rules for creation of low-tech weapons, including crossbows, that take into account changes in 1/2 Damage and Maximum ranges as the bow ST increases.