I personally don't prefer "nostalgia box sets". I like when release is a valid release of this time, not just document of something. This is problem with a lot of music re-issues. It's not just repressing on suitable format, but re-make. You will not get the album, but you get document of the album. Liner notes, changed art, possibly changed sound, and so on. It gives impression as if the album isn't really worth it, other than as documenting it's historical value. I rather would just see albums released as-it-is, same as it always was. Not document of someone's sentimental memories.
I would guess this is one reason why some people do hunt for originals. Simply because they were the real deal. Even if lacking (=read: because) the modern 0dB flat mastering and liner notes.
I guess it is little extra work, to changes ones originals to new editions if one wants to. I would assume in most of cases, the original does not lose the value. Often just the opposite. When more people hear material, collector value may even rise.
For example the Slogun re-issue 2xCD is probably way cheaper than the money you can get from selling away originals. I see discogs prices of some of those businesscard cdr's starts from 18 euros. With selling the 4 CDR's, you not only get funds for this new Slogun 2xCD, but probably 2-5 other new releases? Same applies for all the tape re-issues. To sell original tape, not only you get funds to buy CD re-issue, but probably couple other discs! Of course it demands the mentality of trading/selling... And thinking what is the value of each release. Some would most likely prefer the hand made/hand assembled packaging, directly bought from artists, than any "improved" re-issue.
For example Vinyl On Demand issued statement about stopping distribution of other labels, and his dislike about re-issues, since those re-issues and re-pressings of sold out titles disappoints fans and collectors. It is strange statement from label committed exclusively to re-issues of rarities and obscurities.
If someone really gets his motivation from collecting "rarities" and doesn't want other people to have them, I'm 100% ready to disappoint them any day any moment. It should not be about collectors worrying about decreasing value or disappearing "obscurity", but getting good and inspiring stuff heard by people. I think in past not so many people were so concerned about the potential re-sale value, but simply getting records to listen to. Now it seems to me, for a lot of people, it's most of all the "collectors value" and "re-sale potential" which determines what they buy. Partly as reaction to that, I stopped announcing size of editions of releases. While it would probably add "collectors value" to number many CD's/LP's to mere 100-200 copies, it seems unnecessary. I rather have people buy stuff just for the music, not because of collector potential.