Because you can 3 shot with Thorn in Crucible and no one uses Juju in Crucible. The numbers and PVP complaints are high enough to warrent a buff. The Mythocast got a nerf cause everyone found out how to cheese Atheon 3 times a week so the percentage of players that now own a mythocast far surpassed the numbers Bungie were figuring to work with this early into release.