They would be nice. I'd definitely use grenades more if I didn't have to stash my rifle in the pack first. I'm kind of surprised that there isn't a button or at least a hotkey to reload the equipped weapon. If we had a reload command that withdrew ammo automatically from the sector's stores it would take out most of the annoyance factor of "converting" ammo from one magazine type to another.
Put gun in right hand and a grenade in the left hand. Now when you want to throw your grenade you press the S key and the grenade will move to your right hand ready to be thrown.