What is "realism" in video games?
Bullshit added to fuck over the player in some way, and disguise it under the concept of "but its realistic though!"
Not having health regen be a passive, or losing the entire magazine if you reload too early, however, is a good idea and isn't something new in the gaming industry. It forces you to be more smart with your resources, to know when to reload, and to make your shots count. If you want passive health regen or to not lose your full mag, then...sorry anon, you're a shitter that keeps letting the bugs get too close or doesn't know how to take cover on bots. And on the ammo part, maybe the Deadeye or Punisher might be more your speed?
Again, what even is "realism" in this fucking video game?