I think it happened maybe twice to me in nearly 400 hours of gameplay. After a while, you often know where the weapon spawns are. Or you stock up so much that you don't have the space to grab a gun on the floor anyway.
It's kind of a nitpick really.
Plus, it's very situational, but if the fight drags on for too long, you'll be happy to grab a secondary gun that packs a stronger punch than your 9mm.