Defiant armor was already dropping by the time Crescent Reach opened, so what was the point of creating anything that had lower stats than that?
Actually, we're pretty sure defiant armor is a post-TSS introduction. Off the top of my head, at least one expac later.
The biggest mistake with defiant was making any of it for the under 70 range covered by the already awesome TSS quest armors. Yes defiant is better, but it's also ridiculously overpowered for the content.