Ranged has lower DPS due to full uptime but all other jobs also have full uptime

[Karshan]

Because fights being designed around 2 melee is best and that's what's been done. When you have fights like that, that require uptime strats, casters/ranged trivialize it. If SE starts designing raids around triple ranged (double caster + ranged) then anybody that brings double melee will be at a big handicap. Melees have it the hardest and as such raids designed around them. 4 melees (tanks + double melee) and 4 ranged (healers + ranged + caster). Ideal balance.

SE just overtuned SMN a bit, but I'm sure they'll nerf them again later and put them more in line with other jobs, considering their relative position hasn't changed since their nerf.

Then Square has to add 2 melee class in the pool. Just so that the competition is also 3 classes for 1 spot. Right now with a 2/2 comp you have 50% chances to have a spot with one class as melee while range and casters only have 33%.