I think that's unfair to compare shotgun to devastator. Devastator is a dlc with significant advance on effectiveness against enemies, a weapon with the idea to work on a legend arkship... Plus, it has an amazing amount of clip. Shotgun is a day-one weapon, made in a moment of equilibrium... I aways worked with shotgun damage instead the other ones' range. My reason for moving to Devastator is not because its range, but the amount of effect at shooting... A Devastator with no condition/effect is not a good weapon for my play style, I rather using a shotgun with no condition/effect... In my first experience with devs, I left it off. When friends started to find the boomerangs and grenades effect on shoot, thing became clearly different for me... And for everyone, of course... LOL
Said that, of course range influence got me too... I left my 2million+ GP energy gun off for days rerolling until I find a 2million+ GP SMG. It wasn't just for the range... You guys probably noticed energy gun does not have piercing on enemies... SMG is the only one primary weapon which has it... The more number of enemies closer, energy gun could have 3 millions of gear power, but killing so many enemies each one will probably let u asking for help on the ground. SMG also have a splash in the end of clip... That helps a lot about damage.
With stronger enemies on legend arkship, the combination "energy gun and shotgun" became unviable. For many reasons. Range probably is the main among them, but piercing, amount of boomerangs on effect and clip size are some of the reasons for people to change thoses weapons after the last patches.