I agree, charging shrooms works for resto because as a healer you have some downtime and can heal the normal way whilst they charge, it would be even more painful to throw hurricane / storm into our rotation so that the shrooms are charged for when we need them.
I personally hate shrooms, some people say they want the cata ones back, i still think its always been a clunky mechanic. People say they want an interesting aoe, so that its not 1 button sleeping on keyboard, however it is very difficult for blizzard to balance an aoe that takes more prep and skill on use, since low end players will end up under dpsing, and top end players will end up over dpsing. Unfortunately 1 button aoe is really the most balanced way to do it.
Maybe they could change it so that the Area of effect of the bloom from shrooms increases the damage taken by hurricane and astral storm for all targets by X%, it would mean we have to keep the bloom up, which only needs 1 application of shrooms at a time, unless you want a wider radius, but thats pretty pointless with the raidus of hurricane / storm.