Not that I'm against allowing shuriken attacks as an option, but at the same time, the way the Ninja primary is setup implies to me that your character is not, themselves, a ninja, so I can also see why a longer ranged support weapon, like a bow, would be chosen. Maybe MMs could stand to gain some themed APPs, (like a "Ninja" one with some shuriken and katana attacks, any maybe some kind of defense toggle that also grants stealth, (think Shinobi from Blasters' Ninja Training)...