Yes it is chamber a round and shoot. Its only no use a paperweight etc if you have no ammo. If a loaded firearm is no use why do the military for example carry unloaded when on base why not just lock it up in the armoury. I will answer for you its because they can load it and use it if necessary. It might take a second to load it but that doesn't make it useless.
You assume in every situation that you need a gun that you will indeed have enough time to rack the slide. Not true at all. I am assuming you do not carry concealed. Here is a scenario, you are walking down the street. On the same sidewalk a man is walking in your direction, just as the distance closes and you two are close to each other he attacks you. Tell me where in that situation you would have time to pull out your gun and rack the slide. You certainly cant pull out your gun and chamber a round every time you see someone waking in your direction in public. In that situation, your gun is indeed useless besides being used as a club, or a "heavy expensive paperweight". You say it only takes a second to load, but it also takes two hands to load. Not something you can do while being attacked. Guns were meant to be carried loaded, and safely at that.