Some I shoot, some I don't. I am likelier to shoot an ANIB gun rather than something that really looks unfired, but that's because I hate to destroy value frivolously. If I want to shoot a particular model and I have only an unfired version, I will probably buy a less pristine specimen and have fun with that.
I disagree with the blanket principle that guns are meant to be shot and every gun should be. From the manufacturer's point of view, a gun is intended to be sold. From the buyer's point of view, a gun can be used in whatever way the buyer wants to use it. If that includes staking tomato vines, so be it. If there are buyers who don't get to the range much but just enjoy ownership of fine pieces of machinery, that's their choice and I'm supportive -- even if I don't completely share their outlook.
There is a question of scale here, too. A serious collector with dozens if not hundreds of specimens can't possibly shoot all of them, or at least shoot all of them well. Somebody with a carefully planned collection of four or five firearms specifically suited to different purposes would probably not be a candidate to leave a gun unfired. But then, such a person would be an unlikely owner of, say, a NIB 1910 Triple Lock.