Possibly relevant, but I don't think your assumption is correct there - although at the moment, for defilers, it is that way. During Rohan beta, we were told that defilers' dps was not going to be hugely increased because of balance issues and a desire to see how the Rohan changes worked out before trying to provide defilers with some form of viable dps choice to make. Of course, that view may now have changed or whatever, but I've not seen anything from a dev to say otherwise there. There's a lot of room to be creative with how to provide defilers with that dps option. I'm not holding my breath for it to happen all the same.
As for DR itself, it's so limited really and is very much a lottery on whether it will have any impact on a fight. Reavers are in a decent place once they get impale (R9 if not shop-bought) and their bleeds. Prior to that, their burst damage is pretty poor for a primary dps class. During Rohan beta a number of suggestions were made about changing the skill but none were taken up. Dying Rage can, and should, be a powerful thing. You are guaranteeing freeps hitting you renown by using it so it should at least have some of the lottery element removed given it's a racial trait and on a long cooldown. To be honest, I'd rather see all the racial traits revamped, as they need to be, but that's another I won't hold my breath over. Resetting impale would actually be a subtle but valuable improvement to the skill.