you are not wrong, however, again the idea is that a base unit comprises of xyz, and i believe canon wise all HK units have the equivalent of laminate, weather they are HK-47's, HK-51's or HK-666's.
if you were forced to do a HK on a budget, i agree that padded is probably an ideal swap out.
or alternatively like others have said, say you are damaged drop 10 obligation and take no armor, get it later.
i'm just trying to make a HK unit yard stick, to say this is what your droid should be based on canon, if it isn't this then give a reason why in your character details.
Gotcha.
I'd still say go padded. Fluff wise it can be whatever you want it to be. Call it laminate armor plating and be done with it. If you look up the character Oskara from the beginner game, the armor she is wearing is padded mechanically, but looks like a suit of battle armor. Mechanically, laminate is only different from padded by having hardpoints. It would make sense that a basic HK droid wouldn't come off the line with lots of space for customization ready to go. If it's a stock model then padded mimics a stock plating. Later on, someone could upgrade the HK buy paying 2.5k to add in the modification hardpoints to the armor. Or to swap the stock laminate for one that has hardpoints.