Hello Jaap,
the core business of a registry (at least, that is my personal opinion) is the maintenance of the zonefile, there is overlap with
well, the registries do a lot of database, whois, "IP", lawyers and politics work and one side effect is they produce a zone file.
So, one way to answer your question would be to say that DNS-wg is more concerned with the dns protocol sec then with other things surrounding it.
That's it. The emphasis on "quality" really meant DNS technical and operational quality, like lame delegations, server redundancy, TTL values, future KEY issues and so on. It's not about the accuracy of the whois data or the quality of the registration policy documents. These nevertheless important topics are covered e.g. in the DNR forum. So, do you think that particular sentence needs rewording? -Peter