You need to be able to move, quickly, flop down on the deck, stuff like that!
A forward piece, sticking down, it is in the way. Fix bayonets! Yes it could still happen, think that bit would not be in the way.
You hump a rifle, sling on your shoulder? Sling it off, bits sticking down? Good luck.
Man it's an ar-15/m16 variant if your looking for a gun with nothing vertical I think you've got the wrong rifle. Even without the vertical foregrip you've still got the pistol grip and standard capacity magazines. Not exactly a slim and sleek design.