You want reasons? I've got tons of reasons heres a short list
Advanced Prototype / Tactics
Burst damage is ridiculous
Shoulder Cannon
Faster then a tier 1 mount for 10 seconds (25 second cd)
Shoulder Cannon
Magnetic Blasts damage increase from Fire Burst (w.e its called)
Shoulder Cannon
Assasins/Shadows
Force Shroud on all classes
Stun lock without Stun bar moving (cant remember the name at the time)
Absurd amount of damage
Absurd Mobility
Completely made Lethality/Concealment Useless to practically not played
Sages/Sorcs
Force Barrier
Can heal while in Force Barrier
Force Barriers short cd
Dps specs can heal better then every other dps spec
Force Barrier
Ridiculous damage
And even though the title says nerf. I'd much prefer a buff to arsenal mercenary but until then i don't see myself enjoying ranked or unranked pvp until it happens. Im all for being able to cast tracer missle on the move and never having to stop. But thats equally unbalanced as Sorcs and Tactics so i dont see that happening.