I despise thorn, but it's not overpowered. It's just very strong in the current meta. In an rpg-esque game without normalization of weapons/perks, the pvp is always going to be unbalanced. There will always be a weapon archetype that is more effective then the others. It's just simply not realistic to expect weapons with all different rates of fire, impact, and perks to have the same time to kill. So you can either use the various other weapons against thorn and rely on superior gun skill to carry you through fights, or you can run thorn, as it is very easy to use effectively in its current iteration. Complaining about it is just going to end with a new crucible balancing update that replaces thorn with something else.