if you have a bunch of leg and groin injuries it will prevent you from being slower than 3 thats the main advantage
but it takes up a lot of inventory space and 3.00 speed not really good for fighting... so... this is no reason use a full set but only a Worn Cuirass which gives you extra 4 DEF stat in belt slot + and it's actually quite nice-looking. Maybe on the Doom difficulty it makes some sense.... but I don't know. I personally have never used this set in combat that often because I always have red potions in my pocket that it weighs less and heal 50 by the way it also heals head injuries which lowers magic damage and heals hand injuries which lowers physical damage which by the way this armor set can't do.
So... what do you do if you get a head or arm injury using that armor with 3,00 speed buff in fight?