Well they kept it because they are the single squad with bodyarmor on the model
But to be serious, it brings consistency. Because in order to drop shocktroops models, you actually have to damage them enouth, they wont drop models instanly just because enemy squad managed to lay 4 hits with the voley on 1 model.
Its like having your 1 model instantly being sniped just because it was first to enter into enemy LoS, this is the bad RNG roll of rec.acc. If mentioned unit had armor, then it would have been hit aswell but damage would have been determened by the armor it had, rather then how lucky you are.
Hmm, isn't body armor is sort of a bonus rec. acc. for small arms like rifles and smgs? The higher the pen, the more chance to pen the target. That's why you get higher DPS towards shocks from HMGs and LMGs then from kar98Ks and G43s.
It is very similar to armor penetration and target size. First you need to land a hit, which is (acc.* target size)*100%, then, if you land a hit, penetration chance is calculated (penetration/Armor)*100%. So if the chance to hit is 90% and chance to pen is 60% you get a combined chance to deal damage of 54%.
I think removing armor was a good thing, because it made game less complicated. The damage reduction, which Grens have (
and heavy sappers??) is another story. But again, I started playing in 2019, when all that jazz was long gone.