Your problem is, that you see KB trap only as a KB CC, root trap only as a root CC and not as.. well, traps. That means "fire and forget", that means leaving traps to affect some specific area at some (often) delayed time. BTW necros used to had something similiar in the form of Unholy Hands spell; it used to be AoE fire and forget snare with root when channeling, but got changed to be channeled only, which kinda killed the spell and almost no one is using anymore for the past few years.