Here is an interesting blog about metal detecting from John Winter: http://www.johnwinter.net/jw/2011/11/metal-detecting-the-hobby-and-its-detractors-2/
This particular blog does a good job questioning some of the claims made by the archaeological community. Here is the author's conclusion:
In summary, the portrayal of metal detecting by its detractors is one that few informed people, inside or outside the hobby, would recognise. Their propaganda is characterised by distortions and misuse of statistics to portray the hobby in a negative light. They blur the distinction between hobbyists and criminals that use metal detectors, just as they blur the distinction between archaeological sites and land that has no known archaeological significance. They do likewise with spurious statistics regarding numbers of finds made and recorded, deliberately choosing to ignore the fact that the vast majority of items recovered are of no archaeological or historical significance. However, the reality of the hobby’s contribution to knowledge is plain for everyone to see. It is evident in the display cases of our museums, the records on our databases, and the publications on our bookshelves.
As a coin collector I can empathise-- one can easily substitute "coin collecting" for "metal detecting" in the above post. Though each pastime is different, they are both under attack from the same sources-- academics with little use for anyone but fellow academics.