Without the effects of the grenades it's practically useless. In a game like CoD or Battlefield a smoke completely cuts off fields of view, much like the smoke and blinding. The movement speed is reduced so you can just run through it taking one tick of damage, it would make the smoke very ineffective. And in a game where the enemies have so much health the tick damage makes it easier for a mop up kill. The grenade works perfectly and if it lost any of those effects it would break it.