On Destro - Wouldn't mind RoF having a minor glyph to make it castable on targets or having an 8 or 10 sec duration to take some of the clunk out.
On Demo - I don't find it hard, so much as awkward to play. Entirely personal preference, but I just don't like ToC as a nuke, the HoG gaming, etc. Removing the CD from Meta would help, but the spec just 'feels' off to me. In the '6.0 wishlist' world, I'd still really love to see it become a pure melee spec with DoTs and pets (basically think Unholy DK with DF instead of Runes).
No clunkier than Unholy DK's needing to drop D&D on cooldown.
The only catch is there's no cooldown really on RoF, so you've gotta use a timer or something to warn you when it's about time to refresh. (or eyeball it.)
Did you really just compare Death and Decay which has a 30 sec CD, to RoF which has a 8 sec base duration and which benefits from haste, yet doesn't gain ticks? During Hero/Lust/Meta RoF lasts about 4 seconds. It's way clunkier/annoying to have to place a ground targeted AoE every 4 seconds during haste procs than it is to place one every 30 seconds no matter what.