you want higher tension in the spokes. lower tension causes them to go slack, spokes break from metal fatigue caused by the spokes going slack. lower spoke tension keeps the rim from failing. spokes are really strong compared to the rim, so it's supposed to be a fine balance between what the maximum tension the rim will allow, without being too low that the spokes fail prematurely due to fatigue.
I agree that higher spoke tension makes for a longer lasting spoke. Spokes will fail in fatigue much sooner at lower tensions.