I think they need to balance it out with our over-reliance on haste as a secondary...while I love striking hard and fast in unholy, when switching to my tank spec it feels ponderous waiting for that looong 1.5s GCD. And if I'm RP starved, the unhasted rune CD feels like an eternity, and always seems to come during those "oh $h!t" moments.

Agreed. Unholy needs a better balance between mastery and haste, especially given how much mastery there is on gear in Cata...it still feels weird to be stacking haste as a DK, so much so that, when I tell the DKs in my guild about it (I'm the DK class advisor) they look at me quite oddly. I don't mind being fast but man, it makes playing in any other spec or on any other toon so SLOW.

Since you'll probably have disease up on your target all the time, it's a useful mastery. The resto druid mastery is very useful for tank healing, but less so for AoE healing (during which you more than likely don't already have a HoT on the people you're healing), which is unfortunate as that used to be kind of our niche.