It does infact help with AoE damage, as well as AoE healing but Monk's don't have too many issues there.
On the other hand it uses 2 Chi, most specs tend to have other things they need to spend their chi on (True, Brewmaster has some leeway due to it providing Shuffle)
Xuen, provides great AoE and single target healing as Mistweaver, does nice damage (It does about 8k DPS for me in Mistweaver spec) as well as taking the heat off you when a Brewmaster (Which can be very valuable at times)
Then of course there's Chi Torpedo, making it so whenever you Roll, you also do AoE damage + Healing, for no Mana/Chi/Energy cost. Which is helpful in a number of situations.
So while there's nothing wrong with Rushing Jade Wind, other options available tend to be better or more flexible in their use (RJW would probably be better if it had a slightly lower cooldown or something)