A 1st level fighter with an 18 str has a melee THAC0 of 16, which means he's the equivalent of a 5th level fighter, combat wise (in fact, even better because a 5th level fighter doesn't necessarily do +3 damage). I wonder sometimes if the bonus progression should have been consistently like this:
3 = -2
4-8 = -1
9-12 = 0
13-17 = +1
18 = +2
which would mimic the dex initiative and charisma reaction bonuses. Either that, or 3d6-in-order for rolling abilities is an absolute necessity.