As a titan than used LMGs almost exclusively for most of Destiny allow me to elaborate. Currently all power weapons are burst damage weapons that are condensed into 6 round mags and maybe 1 mag and a few rounds in reserve. BUT they all have a niche. Grenades and Rockets are AOE bursts. Linear Rifles, snipers, fusions, shotguns are single target bursts. Back to LMGs. They are NOT a burst DPS Weapon compared to others (aka 1 hitters) the burst DPS is spread over a 30 - what ever round mag. That makes it much much much more efficient at spreading around damage potential. Where as power weapons can take chinks out of enemies LMGs could take down HOARDS of enemies because it's ammo efficiency. To make the LMG viable they would have had to notch down the damage, which would make them into things like the Sweet business which are just ARs.