I may be missing something about Monk's Falling Thunder

I just finished act 1, so I'm not really far into the game, but I'm not sure about this skill.

It seems cool but, since I added Tempest Flurry, I find it hard to get real use out of Falling Thunder.

Falling Thunder needs power charges, and in order to get power charges I need to get a mob down and cull it, but doing so breaks the rhythm of flurry + bell which would clear the mobs faster than collecting charges + casting thunder would (both killing palm and thunder are quite slow casts).

So with regular mobs it seems more efficient to just attack with flurry and drop some bells which do a lot of aoe damage and don't need any action as bells charges are gained passively just by attacking.

Thunder is also mostly useless on bosses, as there is very rarely a chance to get power charges, and without charges it's useless.

Am I misunderstanding the usage of this skill?