There's always at least one
Edit: I should probably add more to this...
I was originally going to say i'm sure you'd be allowed to rebuild but if you don't want to then I suppose this is -your- problem rather than what's happened to the Arashi. if you enjoyed the multi-target part of the Arashi, I'm sure you can get it added in for your own clan upgrade...
Then again you don't want to rebuild so you're shooting yourself in the foot
Edit Edit: Hey Me again, I wanted to say a bit more.
I believe all the clans were standardized to 100 tokens and a particular power level that Chiyo had in mind. Since the AOE effects were removed I think that Chiyo did that to preserve their 'general viability' in terms of DF. Because -something- had to go to bring everything in line. Would you still be complaining if Chiyo removed bonus damage or bonuses to hit instead of the AOE?
Instead of this rather negative reaction. You should've sent a PM to Chiyo giving him a suggestion for a 'Clan upgrade' that allowed for this AOE ability.