cudaMark: I've heard this line of reasoning. And along the lines of : If there was 100,000 of a certain coin minted (and they're all "identical"), then what does the addition of another one to surface tell anyone about this certain date and mint of coin ? NOTHING. Heck, even low mint coins like a 1916 D: even though a rarer date, it STILL tells you nothing more about the people who went to that park (or beach or forest or desert) than what we already know: That people were recreating there in the 1910's.
However, this too will fall on deaf ears. Because they can counter-argue that the amount of wear on it can tell you when lost. Which can be used in determining when a specific people-traffic was in the area. So it's not the OBJECT that is the "significance". It's the CONTEXT that is the "significance".
And consider, for example, the cool archie work done in the worker villages of the workers who built the pyramids of Egypt: Although those villages are a mile or two (?) upstream or down stream of the actual pyramids (hence outside the "sacred zone" of "obvious sensitive monument", right ?). You realize they're finding out a bunch of cool things about the workers who lived there and built the pyramids, which lends to us knowing things about life at that time.
So if a person 2000 yrs. ago had had your attitude, and thought "how much more does a denarius coin tell that we don't already know ??". And if those evil "looters" back then had been plucking up metal artifacts and moving them out of context, then you and I, 2000 yrs. later, wouldn't be benefiting from the cool info that arises from seemingly innocuous metal objects they finds.
How can you live with yourself ? Don't you feel the SLIGHTEST tinge of guilt for "denying those future generations" to learn about their past ? We are utterly disappointed with you. I refuse to detect with you anymore. HAAaaarrruummmppphh !