Back in the WotLK runes were double regenerative, they have changed it and buffed abilities if i can remember correctly, fixing rune regen at 6.6 is not possible because then unholy presence will provide nothing, haste will provide nothing but faster melee strikes, and class will be gcd capped.
I don't think Chillblains is the new desecration for unholy, because desecration was providing pillar snaring and was aoe snare, yeah with rolling blood chillblains is close to desecration, but I really feel Chillblains is "so frosty" and deserves to be frost passive just my personnel taste
About DnD, I just can't imagine in what situation having your diseases undispellable within small radius is worth a talent? Since reapplying diseases is so easy, wasting a talent to make them undispellable in a small radius seemed to luxury to me.
Like you, i always dreamed to have some absorbsion effect to Necrotic Strike, but this will stay as dream you know