このNA向けのインタビューの中で、吉田は二刀流ならなかった理由を言いました：
Will Ninjas have an offhand slot for traditional throwing items such as shuriken?

No, we're actually not thinking about having something equipped in another weapon slot because it makes it kind of unfair to the Ninjas who actually then have to gather more items than another type of player, and then also have to start thinking about going into battle and deciding how many shuriken or how many daggers they have to buy. It just creates more work for that Ninja. We'd rather cover the throwing weapon in actions instead. We'll be able to talk a little more about it as we get closer to 2.4

http://massively.joystiq.com/2014/06...sses-and-more/
要するに左手と右手が別々武器になると、シ/忍が他のクラスより多く装備収集の努力が強要されるので不公平になる。
そして手裏剣や投げダガーを消耗品にすると戦闘の前にお金や資材を消費させ、在庫チェックなど苦労になるので単純にアクションにする。

そして「忍者のZW欲しければ今からアートマ収集行け」という発言もありましたw