Technically, the good thing about the shuriken is that it counts as ammo, and thus it's easy to enchant. Flurry technically doesn't apply to it because a monk can only use flurry with melee weapons - stupid, I know, but there you have it.
Technically, it specifically states you can flurry with shuriken.
There's nothing in there about melee weapons, just a list of what you can use. I tend to agree with you, but they're so minor (and really, every ninja movie you see has them flinging shuriken around) that it's not a big deal.
So, I was right on the whole? That doesn't really happen a lot, but yeah, I think we can agree then that as a monk weapon, TWFing, flurried, free action to draw, easily enchanted makes the shuriken likely worth some exotic pre-reqs to be used that way. Can Rapid Shot/Many Shot/similar feats also be added in and used in conjunction with some combination of these other features? Then again, if someone apparently has to meet so many requirements already simply to be able to do all that in the first place... are there really any pre-reqs to add? Probably not... maybe it was a moot point from the start...
I just checked on the monk's flurry of blows ability - no mention of it being melee only. But then again, the shuriken is the only ranged weapon on that list. Pretty much everything that applies to ranged throwing weapons applies to shuriken, but I don't think you can flurry and use Rapid shot/Manyshot with it. And even as a throwing weapon it's not much to look at. The range is pathetic, so is base damage and crit, and the only class that might get some use out of the thing can't use the class feature that has to do with it efficiently.