Assault Spec has just as much burst, you can get 2 HiB's, 2nd from proc, within 3 seconds of eachother. Also Burst isn't simply high numbers, the casted abilities along with the dots in that period of time does just as much damage, and it continues to do consistent damage to be able to kill those healers.
I'm sorry but Gunnery's damage is from casted abilities. I can run around in circles doing hammer shot, incendiary, and HiB and do about an adequate 2400 dps. That is Mobility. Assault spec also has useful cooldowns like Suit Foe for things like mind crush that aren't cleans-able by us, and Electro Shield for surviveability while doing damage. It also can run efficiently at lower ammo regen (3/4 ticks) for those prolonged PvP fights and burst raid phases. Lastly, it allows you to use Plasma Grenade off cooldown due to the reduced time on recharge cells and reserve powercells. Plasma Grenade being the best Dot and hitting initially about the same as a Grav round.
I want my representative to be knowledgeable, to always be trying new things and new hybrid specs and stuff. Not to dismiss things based on rumor or because it doesn't work initially.
I have made this spec work to my advantage, I know it works. Other specs work for other people, I've even seen a nice gunnery/ incendiary round build for example. But to say this spec is simply bad is not the type of attitude I'd want in my representative.
Here are more off topic reasons if needed:
1. The Serendipitous Relic:
In the 6 seconds that you are granted the power, I am guarenteed 1 High impact bolt and 5 ticks from plasma cell or incendiary round VS. 3 grav rounds, and maybe a full cast of full auto if you're lucky it procs at the same time the relic does. This ties into the burst of PvP.
If you remember in pre 2.0, Vanguards were considered by many to be overpowered due to the increased damage by burn effect at sub 30%, among other things. When it comes to finishing people off in PvP I can use both the casted abilities and the dots themselves do more damage to finish the job. The dots themselves are pretty much an execute like spinning strike and quick draw because of the talents in the spec.
3. Free Crit
As you know crit got cut significantly in 2.0. This is more of a PvE thing in importance, but by going pure power I have about 27% ranged crit. This is because of the spec and the cell I am in. Compared to gunnery going pure power I'd have 19% ranged crit. Charged Bolts also has higher minimum damage and utilizes the set bonus' 15% crit buff to maximize the crit multiplier.