In early DF builds all DKs had access to both types of rune regeneration.
Than they changed it to go back as on live with Unholy having Runic Corruption and Frost having Runic Empowerment (the better choice if you ask me).
They talk about of reworking the resource generation to balance the idle time, while they forced Unholy back to Runic Corruption after they decreased the Runic Power consumed by Death Coil.
The % regen proc chance was different between RE and RC because Unholy had more expensive skills runic power wise.
DKs still have RNG in the resouce generation. How is that still a thing? The Virulent Plague was nerfed, sorry changed to not stress the servers with RNG. Why is the rune regeneration still based on RNG?
Now, after all ther thinking and “balancing”, Unholy got out with the short stick in terms of rune regeneration.
It’s still bad for both becasue of the RNG, but now whorse for Unholy.