Quote Originally Posted by Watchman
'Cause it's a simple, cheap and cheerful way to provide foot soldiers in particular with some ranged punch that can be used to inflict casualties and disorder in the enemy ranks before close combat. The tactic actually survived pretty long into the Middle Ages, although Europeans weren't overall that fond of it anymore. Nonetheless period sources often refer to javelin-throwing being regarded as part of the proper training of a good soldier, and even knights practised it; they're also mentioned in use by light cavalry in some fairly late-period battles.
Europeans were fond of it, actually, they just used more primitive missile weapons, like the hurlbat, or heavier throwing spear. They lost the javelin aerodynamic shape or thongs used to give them greater range.

Javelin throwing is a learned skill, and Roman infantry practised it until the 1400s. The problem in Europe is that most soldiers were merely farmers given some rudimentary training ;)