To represent the text as originally written, I need a digital representation for each of the characters in it. Since all I want to do is reprint the book -- I don't need to use the unusual characters in interchange -- the PUA and a commissioned font seem just perfect to me.
In the modern world many forms of publication require interchange. For example, anything that's HTML based does poorly with non-standardized characters. So does storage in databases. If you can conceive of a digital re-edition of a prominent work (including citation from) and can assume that there's some realistic chance that technologies other than faximile or PDF would be brought to bear, then you have the interchange requirement, even if noone uses the notation for new text.
Over time, I'm becoming more supportive of Michael's stance of inclusiveness in that direction. As a matter of basic parity, I just don't see why we take such great pains to standardize extremely rare forms of Han ideographs, but baulk at supporting our own writing system and its extensions equally faithfully.
That doesn't mean that we stop asking all the hard questions, but that we allow a presumption of usefulness for characters that were in demonstrated use over some time and by several authors.
A./
