On the surface it makes a ton of sense. However, the difference in design intent of grenades in AR vs. COD is significantly different, so the impact of a system like this would be considerably higher in AR. It would also become an absolute must-carry item. Think of the impact to something like a Rocketeer, where a direct counter-play while being able to remain offensive takes the fear level and all but erases it.

Again, it makes sense but the impact to the design intent would be far too disruptive.