This is the trade-off for having super easy target acquisition and target maintenance (keeping target in range and in your firing arc). Let's face it, even a noob playing a Merc can keep an enemy target in range and in his firing arc 90% of the time. But a noob on a melee struggles to do that 50% of the time. So the devs counter that by making Mercs have the lowest utility in the game, the lowest damage output amongst dps subclasses, and the lowest survivability in the game. The problem is that amongst skilled melee players, their uptime increases dramatically while for skilled Merc, you are still stuck with the same STRUCTURAL handicaps. The devs have not fixed this, nor are ever likely to fix this because from their perspective, the meta average productivity of the classes is balanced. But from the player perspective the situation is fubar. Mercs are OP amongst low skill players and are worthless amongst high skill players.
While I don't disagree, Merc/mando doesn't benefit from any advantages re targeting that the other ranged ACs don't also possess. Quite the opposite, GS/Sniper and some builds of Sorc/Sage have greater range, as well as far more ample toolkits (immunities, dmg mitation, escapes/movement, etc.). But I get what you're saying re meta averages, and I think you're right that if the fix didn't come with 2.0, then it probably never will. Merc/mandos will just have to learn to love Suicide Mode PvP gameplay, learn to heal (and be 3rd best), or re-roll.