Just for two reasons. One, its incredibly easy for other teams to soak each and every trap or silence/stun the hunter during scatter. Two, because every other dps in the game has a guaranteed instant CC.
If it becomes a shot it would be comparable to Blood Fear, PoM Sheep/Ring, NS/PS cyclone, NS/MW Hex, IS, the list goes on.
If it becomes undispel-able then teams constantly soaking traps would have to actually manage their CDs around hunters. I understand this would be on the OP side of things, but its a thought.
It is just really hard for my to wrap my head around classes with more pressure having more CC than classes with less.