yeah, but why many javelins are less effective than arrows?
haven t javelin more weight than arrow?
Many horse archers and archers have 5 or 6 of missile attack, the same point of skirmishers: then javelin should be more powerful, in my mind.
2 armoured skirmisher cavalry suck against 1 unarmored horse archer cav(especially raiders witch can charge).
With EB1 units stats, i prefer to take archers than skirmishers, because archers can easily kill all enemy skirmishers before they come near my army.

Post Scriptum
About roman pilum: this is only weapon that can save legionaries from extra heavy cavalry charge... PLEASE MAKE IT MORE POWERFUL, almost like spanish solifera (6 of attak).