> They 
> could but they
> don't as not many people are interested in that information. 
> Unlike artists,
> catalogers get little (no) recognition for the catalog 
> records they create.
> So we end up with a situation where we may be creating an 
> extension which
> nobody wants to use.

Within a classical library context, I would agree - however SRW is
aiming beyond that sphere.

For instance I might be using SRW to search (and the proposed Update
profile to maintain) a community built index of books or web pages,
where anybody is encouraged to add new metadata records about resources
(there are plenty of such community indexes emerging on the web). In
such cases, a potential user is as interested in the provenance of the
metadata as much as the described resource.

There are numerous variations on the same theme...