Fact is anything heavier than leather makes you a very slow target with rifles equipped.
Player DT is not really worth it as anything firing low - mid ap rounds comes in groups and lowers health just the same, anything stronger and fast is going to ignore any DT so go for looks.
My latest characters stuck to merc outfits, and with a good selection of energy weapons takes down anything quickly while staying at range due to fast movement.
Are we playing the same game? few enemies use AP rounds, in fact almost no foe uses AP rounds. I can't recall a foe off hand other then the deathclaw who simply ignores DT.
Now if your fighting a nighstalker or something in melee you might think it ignores DT it doesn't the damage is just three times what the stylish light armor gives. I have to ask what is the highest DT you've played the game with 16? Taking 30dmg instead of 70 is always a good decision and the speed penalty from heavy armor is incredibly minor.
I wear MK2 when it hits the fan, but that’s mostly for realism.
MK2 is the ugliest armor in the entire game series,