In a way, it is “kind of” the same thing that I suggest, or at least it is very similar. Let met explain :
There are 3 categories of perks:
-Mobility
-Vitality
-Weapons
The +35% vitality perk from the vitality category is the most expensive: it costs 16 perk points.
If you choose to get this perk, you won’t be able to choose a lot more of other perks in the vitality category, because you generally get 16 points or a bit more for each category (some soldiers don’t even have 16 points, it is common to see some soldiers having only 15 points, and some even less). And as a result, you won’t be able to buy a lot of other perks if you have more than 16 points in the vitality category, or even not at if you just have 16 points.
And what are the other perks in this category ? The perks for extra endurance, endurance regeneration, health regeneration, health given by medkits, holding breath time, stability after taking damage and shaking reduction perks.
So, if you buy the +35% vitality perk, you will very likely not be able to buy a lot of the perks cited above, maybe not even a single one if you only had 16 perk points to begin with, or you might not even be able to buy the +35% vitality perk because you never even had 16 points to begin with, thus preventing you to equip body armour cosmetics for this case.
And generally, the vitality category is the one that gets the least amount of perk points, so it is often that you see a soldier having only 15 perk points for the vitality category, so I think that my suggestion would limit the amount of soldiers who wear the body armour cosmetics.