I´m not sure about that.
This will get a DOWNVOTE because i aren´t a fan of arcade shooter thats why i playing Arma.
Maybe you are right about that a kevlar vest hold up to 4 bullets until it will be penetrated and it would be "MORE REALISTIC" but in my opinion Arma Soldiers don´t need more armor.
Don´t think it is the right way.
More Hitpoints until someone die or get injured is crap and only for people who wants to be rambo.
IF this feature really comes to Arma Bohemia Interactive should have a plan how to disadvantage players who carry heavy armor.
In my opionion this feature would be a very bad idea.
People who wants more hitpoints should play another game.