I'm not even sure Dark Arts would be compatible with how drk is now. We've got one spammable gcd and the rest all have minute cooldowns or higher.
Adding Dark Arts effects to that would just make casting each skill require 2 weaves instead of 1, and I doubt you'd want to be spamming Dark Arts onto Edge of Shadow between every gcd.

I'd much rather they just focus on putting utility on the skills directly, and flesh out the TBN break system we have right now.