I'd like to propose that PGAdminIII add support for modifying data using the Edit Grid for VIEWs as well as regular tables.
It seems the naive approach of running an INSERT, UPDATE, or DELETE statement and relaying any errors back to the user should be relatively safe. If there are rules defined that allow write access to the view, then it should work fine. If not, then they just get an error message.
I guess the argument against this is that normal Edit Grid changes are guaranteed to affect exactly one row (identified by OID or primary key), while we can't gather that information from a VIEW. I'd like to be able to do it anyways, so maybe hide it behind an option like "Edit (and potentially destroy) Data"