It is already this way. You rend and rend again when there is less than 5 sec left and final burst detonate sooner. So it is nice to make a habit of refreshing rend on multiple targets when your main target rend is less than 5 sec left.
That's not "early" though and doesn't help whatsoever when trying to kill low HP shit like mushrooms, totems, void tendrils and whatnot.
Instead of a final tick, make Rend do that damage when applied but only when applied to a target that currently has no Rend applied or a Rend applied that has <5.4 seconds left.
It'd allow Arms to kill low HP shit within one GCD for some rage while not having a significant effect on DPS or your rotation overall(see: PvE). The requirement for the damage only to apply when there's no Rend or a short duration one on the target makes sure people don't just spam Rend instead of WW as a filler.
This would have an extremely minor effect on PvE (slight decrease in ramp up time) and thus should be easy for Blizzard to implement without having to fear about Arms dominating cleave fights even more.
Edited by Hidden, 23 December 2014 - 08:21 PM.