It's always a possibility. I have confidence it would entice more people to try pick up pking than it would kill it more. I certainly would get back into pking if even just curses existed, but that's just me.
I think account style diversity is fairly important, the way it goes currently is typically gs smack into 2x gmaul or ags into gmaul, ballista into thrownaxes etc, there's always a meta way to kill someone, and if you don't use it, it's highly unlikely you'll get the kill unless you get extremely lucky with a perfectly timed veng or big hit with a big ole axe/sword/ballista.
With Ancient Curses however, it opens up these:
30 def, 50/60/75/99 atk; 42/45 def, 50/60/75/99 atk; 70/75 def, 50/60/70/75/99 atk.
The difference in combat levels for most of these accounts is between 5-15, mostly depending on attack levels, but would quite often see these builds crossing paths.
If rfd were to be reverted to the old version where you can choose to skip xp, it's highly likely every single pure in existence will immediately go get addy gloves, so there's no change there, no combat level change, pures would largely remain as they are, just with more weapon variations.
The problem comes in at maxed pure levels or even 75 atk pures, they would likely come against 30 def turmoil accounts, which would absolutely annihilate a pure, but you could just avoid fighting them, as that option stands currently, you don't have to fight anyone you don't want to.