SirTawmis: Speaking of this - why do games get delisted?
Does this come from the IP holders?
It's a shame - like the original poster - sometimes I want to revisit the childhood memories and play these older games as they were. (Most of my library is Sierra games like Space Quest, King's Quest, etc). So I definitely enjoy revisiting the past - and sometimes hearing that odd beeping sound that passes as music, or even clunky controls is kind of fun to relive.
As a side note to add - I had MYST on my wish list and got an email that it was available. And it's not the original which is what brought me here to look this up. :)
Darvond: Well, in the case of Myst, it comes from their own hand, since Cyan own it.
There's two major reasons.
1) The more technical reasons; that maintaining such old things on new code would be a technical nightmare. (See Creatures, Interstate 76, etc.) I'm not even sure if modern graphical cards support the low resolutions or color depths anymore.
2) The Canon reason. These old titles no longer even remotely match to the idea of which represents the MYST universe.
1) realMyst (1.11) still run more or less perfectly in compatibility mode on my win10 laptop from last year. Generally Plasma engine games seem to have aged relatively well compatibility-wise. The only one I've ever had any major problems running on newer computers has been Myst V (which uses the more graphically complicated Plasma 2.1). Uru and Myst V which also use Plasma are still sold on Gog.
2) No elements of the plot or lore has been changed between realMyst and realMyst ME. The only plot changes between newer Myst and the original Myst was the inclusion of Rime (which was removed again in the 2021 version anyways) and of Ti'ana's grave (which has been in all new versions since realMyst). Some of the lore surrounding Uru (and to a lesser extent Myst IV) do contradict with the events of Myst, but none of that is reflected in any version of Myst.