I think people in this thread are focusing way too much on the damage that tracer/grav does and NOT on the relative damage it does for what it is. Most everyone agree's that both skills are FILLER attack and not meant to be the primary nuke/burst attack for the respective AC's.
That being said because its a filler, who's sole purpose should be stacking a buff/lining up the stars for a big amount of burst dmg, the sheer amount of damager per cast time and resources is outrageous.
That often-linked video was to prove a point. Not that you can do lots of damage to low level players who don't pay attention, but to show just how powerful this supposed filler can be...without using any of those other attacks.
Yes its interrupable, yes you can los..yes you can focus the class down. The point is that for what its supposed to be, its just too damn good.
Lightning strike doesnt hit anywhere near that much, force lighting doesnt do anywhere near that much. Does chain lightning hit that hard? no...and it has a 15 sec cd. Even with wrath procs it will barely touch 3k. I'm not saying BH/Trooper needs a nerf at all, just need to reallocate some of the damage to other skills. Hell even operatives/scoundrels have to pop long cd's to do that sort of burst...