Genealogy and the purpose of archives

At the Small Religious Archive (SRA) where I presently work, genealogy is big part of what we do. These kinds of queries represent the vast majority of queries we receive from the public and much of the research to answer them is often routine, as people are generally interested in vital statistics. I enjoy writing detailed letters back to users detailing the research done, but on some occasions, nothing could can be found and this is terribly frustrating. There was recently someone who wrote in from the West coast (which is far away from SRA) with a complex request, but it turns out that we didn't have anything on any of his ancestors. He was a little vague as to whether or not his ancestors would be covered by SRA.

I wonder how archivists should respond to what I might call the Genealogical Fact and how this Fact impacts the broader purpose of archives. The Genealogical Fact is that most (or a plurality, at least) archival users (I'm bracketing major governmental archives like the LAC etc) are interested in researching their family history. These people tend to outnumber all other kinds of researchers dramatically, whether they be academic historians, lawyers, activists (I would be fascinated to see some data on how important archives are to legal disputes such as resolving native land claims) and so on. Serving this community of users is generally quite rewarding, as you help someone to find out about their family's past. Beyond that, however, it is good for publicity. As a Globe and Mail column argued some years ago, archives have a very low profile compared to analogous 'knowledge institutions' like museums or libraries (school students are almost certain to have visited at least one museum or library during their studies, but an archives? Unlikely. I certainly never did until I was most of the way through my undergraduate studies).

Further, given the realities of limited budgets and limited storage space, should archives try to accommodate and tailor their future acquisitions with genealogists in mind? If so, to what extent? Obviously, most (all?) archives are mandated to preserve certain material, regardless of the likelihood of it ever being used. I am personally quite interested in preserving records that are of general historical interest, but is the Archivist's personal interests important enough to determine the purpose of Archives?

How does one balance an Archives mandated mission (e.g. preserve records according to legislation), the Genealogical Fact and items of general historical interest?