To hide those parts, all the armour chest pieces would have to be redone. Currently the chest piece and tassets are part of a single model. To hide it you'd have to separate them into two distinct parts, with the ability to toggle the tassets.
You'd have to make sure the animations were correct when the tassets were shown, as they are now 2 separate objects anchored at a point. This might introduce it's own problems.
Easier to do would be single armour parts. Shoulders for example. That wouldn't take nearly as much work.
I'd be happy if they'd just stop with the tassets (the "hip pads") on chest armor.
They ruin the look of so many otherwise nice looking armor styles.
And they look even worse when your character is in motion.
The Dro-m'Athra motif currently in the store would have been a crown purchase for me if it weren't for the tassets on every chest piece. WAY too gaudy.