If you factor in the cast time of Rune of Power, but ignore that you can line it up with other cooldowns, it’s pretty much equal already.
RoP has a ~1 second cast time (with haste) every 45 seconds, thus you get 12 seconds of 140% damage and ~32 seconds of 100% damage. Icy Veins drops an extra rune, so that’s another 12 seconds around every 90 seconds or so (not sure how often you cast IV, but definitely more often than once every 180 seconds). So… let’s say 3 * 12 = 36 seconds of RoP with two seconds of casting it, so (2 * 0% + 36 * 140% + 52 * 100%) / 90 = 113.8%.
That’s also assuming you are casting it exactly on cooldown, which potentially negates the ability to line it up with other cooldowns… Then, if you have to abandon your precious rune, you’re in the gutter (damage-wise).
I recently edited the macro that had RoP bound to alt-2 and changed it to Shifting Power since I haven’t played RoP in ages… Liberate yourselves - mobility is power.
What does need a buff is the water elemental… The price for the utility is very high. I use it when playing solo, but that’s generally on trivial mobs and the power difference is very noticeable. It is extremely niche right now and not a viable “all situations” talent like RoP and IF are.