It enhances afk combat macro's by allowing u to do auto-attacks instead of just specials from the toolbar.
Make a macro that does this (this assumes ranged weapon or your in melee range)
ObtainTarget:
/ui action cycleTargetOutward;
/pause 9.5;
/target self;
/pause .5;
/m ObtainTarget
NOTE: If you want to target mobs in a 360 degree radius try hitting CTRL+SHIFT+S, that will orbit your camera around too.
Thats just a basic version, you can add in heals, re-apply powerups, AOE's etc for better effectiveness.