>>536499690
Aside from looks, the only reason I can think of to run heavy armor is to have 150 armor-rating while getting some passives like Fortified, Engineering Kit, the medic crutch, or Rainbow Six Siege Season 69 Liberation of Israel Ready.
Extra Padded medium armor already gives you 150 AR while letting you move at medium speed.

Its less of a detriment on bots because the majority of times you die are insta-kills that ignore your armor, or you get ragdolled just to die to impact damage.