Is there a reason why this is so horrifically bad?
You have to be just about perfect in lining up Lacerating Blast as it is a cone effect that seems to only be 25 to 30 degrees wide at the maximum range of 10 meters and seems to be only 5 or 10 degrees wide at the character. And it doesn't seem to always transfer the DoT even when the stars align and you line up a group of mobs appropriately.
While the class has stealth and there has to be some trade offs, when you pull a group you have to do 2 separate attacks to get your DoTs down,(Shrap Bomb and Vital Shot), at which point the mobs are likely in a circle around you making it almost impossible to spread the DoTs with Lacerating Blast. This then forces you to single target the mobs down.
The other classes dependent on DoT spreading for maximum damage, Vigilance Guardian, Watchman Sentinel, Serenity Shadow and Dirty Fighting Gunslinger all seem to have 10 meter diameter circles when DoT spreading making the Ruffian arguably deficient to those classes.
(Essentially an area of 78.54 meters for the circular effects compared to approximately a quarter of that value between 20 and 25 meters of surface area for the Ruffian)
It needs addressed, although, this seems to be a long term issue and Bioware/EA is unlikely to look at it.