Macro Target's name in chat

[Niwashi]

/ac "Eye for an Eye" <2>
/ac "Eye for an Eye" <t>

Will cast on tank if no one is targeted, and will cast on target instead if you choose a target.

I think you got those the other way around. In order to cast on your target when you have a (valid) target, the <t> line should come first. Then let it default down to <2> on the second line of the macro for when you don't have anything targeted or have an enemy targeted.

But you're quite right on your overall point about how flexible these macro options are.