[Suicide Junkie]

Note that that would have to be a damage list, since a ship could be hit by different types of damage.

How would you arrange that your shield depleters hit before the normal damage weapons?

Also, it could cause a problem with targetting decisions:
It would really suck if your fleet of 10 baseships, full of WMGs unloaded all their shots into a single escort, simply because it hasn't blown up yet.
With sequential firing, the AI is forced to keep choosing new targets when the first ones are dead.